diff --git a/README.md b/README.md
index 53a4c7a4..d3fbf154 100644
--- a/README.md
+++ b/README.md
@@ -1,14 +1,17 @@
-# scssphp
-### <http://leafo.github.io/scssphp>
+# This repo has been archived
 
-[![Build](https://travis-ci.org/leafo/scssphp.svg?branch=master)](http://travis-ci.org/leafo/scssphp)
-[![License](https://poser.pugx.org/leafo/scssphp/license.svg)](https://packagist.org/packages/leafo/scssphp)
 
-`scssphp` is a compiler for SCSS written in PHP.
+#### Please go to https://github.com/scssphp/scssphp
+
+----
+
+## scssphp
 
-Checkout the homepage, <http://leafo.github.io/scssphp>, for directions on how to use.
+![License](https://poser.pugx.org/leafo/scssphp/license.svg)
+
+`scssphp` is a compiler for SCSS written in PHP.
 
-## Running Tests
+### Running Tests
 
 `scssphp` uses [PHPUnit](https://github.com/sebastianbergmann/phpunit) for testing.
 
@@ -38,7 +41,7 @@ To enable the `scss` compatibility tests:
 
     TEST_SCSS_COMPAT=1 vendor/bin/phpunit tests
 
-## Coding Standard
+### Coding Standard
 
 `scssphp` source conforms to [PSR2](http://www.php-fig.org/psr/psr-2/).
 
diff --git a/composer.json b/composer.json
index 62153e7b..eaa8e87b 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
         "psr-4": { "Leafo\\ScssPhp\\Test\\": "tests/" }
     },
     "require": {
-        "php": "^5.6.0 || ^7"
+        "php": "^5.4.0 || ^7"
     },
     "require-dev": {
         "squizlabs/php_codesniffer": "~2.5",
@@ -39,5 +39,6 @@
             "/phpunit.xml.dist",
             "/tests"
         ]
-    }
+    },
+    "abandoned": "scssphp/scssphp"
 }
diff --git a/scss.inc.php b/scss.inc.php
index 8a3cfb83..2a5f0774 100644
--- a/scss.inc.php
+++ b/scss.inc.php
@@ -1,6 +1,6 @@
 <?php
-if (version_compare(PHP_VERSION, '5.6') < 0) {
-    throw new \Exception('scssphp requires PHP 5.6 or above');
+if (version_compare(PHP_VERSION, '5.4') < 0) {
+    throw new \Exception('scssphp requires PHP 5.4 or above');
 }
 
 if (! class_exists('Leafo\ScssPhp\Version', false)) {
diff --git a/src/Cache.php b/src/Cache.php
index 1e12770a..49cf631b 100644
--- a/src/Cache.php
+++ b/src/Cache.php
@@ -18,10 +18,10 @@
  *
  * In short:
  *
- * allow to put in cache/get from fache a generic result from a known operation on a generic dataset,
+ * allow to put in cache/get from cache a generic result from a known operation on a generic dataset,
  * taking in account options that affects the result
  *
- * The cache manager is agnostic about data format and only the operation is expected to be descripted by string
+ * The cache manager is agnostic about data format and only the operation is expected to be described by string
  *
  */
 
@@ -32,38 +32,36 @@
  */
 class Cache
 {
-
     const CACHE_VERSION = 0;
 
-
     // directory used for storing data
-    public static $cache_dir = false;
+    public static $cacheDir = false;
 
     // prefix for the storing data
     public static $prefix = 'scssphp_';
 
     // force a refresh : 'once' for refreshing the first hit on a cache only, true to never use the cache in this hit
-    public static $force_refresh = false;
+    public static $forceFefresh = false;
 
     // specifies the number of seconds after which data cached will be seen as 'garbage' and potentially cleaned up
-    public static $gc_lifetime = 604800;
+    public static $gcLifetime = 604800;
 
-
-    // array of already refreshed cache if $force_refresh==='once'
+    // array of already refreshed cache if $forceFefresh==='once'
     protected static $refreshed = [];
 
-
     /**
      * Constructor
+     *
+     * @param array $options
      */
     public function __construct($options)
     {
-        //check $cache_dir
+        // check $cacheDir
         if (isset($options['cache_dir'])) {
-            self::$cache_dir = $options['cache_dir'];
+            self::$cacheDir = $options['cache_dir'];
         }
 
-        if (empty(self::$cache_dir)) {
+        if (empty(self::$cacheDir)) {
             throw new Exception('cache_dir not set');
         }
 
@@ -75,40 +73,42 @@ public function __construct($options)
             throw new Exception('prefix not set');
         }
 
-        if (isset($options['force_refresh'])) {
-            self::$force_refresh = $options['force_refresh'];
+        if (isset($options['forceRefresh'])) {
+            self::$forceFefresh = $options['force_refresh'];
         }
 
         self::checkCacheDir();
     }
 
-
     /**
-     * Get the cached result of $operation on $what, which is known as dependant from the content of $options
+     * Get the cached result of $operation on $what,
+     * which is known as dependant from the content of $options
+     *
+     * @param string  $operation    parse, compile...
+     * @param mixed   $what         content key (e.g., filename to be treated)
+     * @param array   $options      any option that affect the operation result on the content
+     * @param integer $lastModified last modified timestamp
      *
-     * @param string $operation
-     *   parse, compile...
-     * @param $what
-     *  content key (filename to be treated for instance)
-     * @param array $options
-     *  any option that affect the operation result on the content
-     * @param int $last_modified
      * @return mixed
-     * @throws Exception
+     *
+     * @throws \Exception
      */
-    public function getCache($operation, $what, $options = array(), $last_modified = null)
+    public function getCache($operation, $what, $options = [], $lastModified = null)
     {
+        $fileCache = self::$cacheDir . self::cacheName($operation, $what, $options);
 
-        $fileCache = self::$cache_dir . self::cacheName($operation, $what, $options);
+        if ((! self::$forceRefresh || (self::$forceRefresh === 'once' && isset(self::$refreshed[$fileCache])))
+            && file_exists($fileCache)
+        ) {
+            $cacheTime = filemtime($fileCache);
 
-        if ((! self::$force_refresh || (self::$force_refresh === 'once' && isset(self::$refreshed[$fileCache])))
-          and file_exists($fileCache)) {
-            $cache_time = filemtime($fileCache);
-            if ((is_null($last_modified) or $cache_time > $last_modified)
-              and $cache_time + self::$gc_lifetime > time()) {
+            if ((is_null($lastModified) || $cacheTime > $lastModified)
+                && $cacheTime + self::$gcLifetime > time()
+            ) {
                 $c = file_get_contents($fileCache);
                 $c = unserialize($c);
-                if (is_array($c) and isset($c['value'])) {
+
+                if (is_array($c) && isset($c['value'])) {
                     return $c['value'];
                 }
             }
@@ -118,43 +118,45 @@ public function getCache($operation, $what, $options = array(), $last_modified =
     }
 
     /**
-     * Put in cache the result of $operation on $what, which is known as dependant from the content of $options
+     * Put in cache the result of $operation on $what,
+     * which is known as dependant from the content of $options
      *
      * @param string $operation
-     * @param $what
-     * @param $value
-     * @param array $options
+     * @param mixed  $what
+     * @param mixed  $value
+     * @param array  $options
      */
-    public function setCache($operation, $what, $value, $options = array())
+    public function setCache($operation, $what, $value, $options = [])
     {
-        $fileCache = self::$cache_dir . self::cacheName($operation, $what, $options);
+        $fileCache = self::$cacheDir . self::cacheName($operation, $what, $options);
 
-        $c = array('value' => $value);
+        $c = ['value' => $value];
         $c = serialize($c);
         file_put_contents($fileCache, $c);
 
-        if (self::$force_refresh === 'once') {
+        if (self::$forceRefresh === 'once') {
             self::$refreshed[$fileCache] = true;
         }
     }
 
-
     /**
-     * get the cachename for the caching of $opetation on $what, which is known as dependant from the content of $options
+     * Get the cache name for the caching of $operation on $what,
+     * which is known as dependant from the content of $options
+     *
      * @param string $operation
-     * @param $what
-     * @param array $options
+     * @param mixed  $what
+     * @param array  $options
+     *
      * @return string
      */
-    private static function cacheName($operation, $what, $options = array())
+    private static function cacheName($operation, $what, $options = [])
     {
-
-        $t = array(
+        $t = [
           'version' => self::CACHE_VERSION,
           'operation' => $operation,
           'what' => $what,
           'options' => $options
-        );
+        ];
 
         $t = self::$prefix
           . sha1(json_encode($t))
@@ -164,38 +166,35 @@ private static function cacheName($operation, $what, $options = array())
         return $t;
     }
 
-
     /**
-     * Check that the cache dir is existing and writeable
-     * @throws Exception
+     * Check that the cache dir exists and is writeable
+     *
+     * @throws \Exception
      */
     public static function checkCacheDir()
     {
+        self::$cacheDir = str_replace('\\', '/', self::$cacheDir);
+        self::$cacheDir = rtrim(self::$cacheDir, '/') . '/';
 
-        self::$cache_dir = str_replace('\\', '/', self::$cache_dir);
-        self::$cache_dir = rtrim(self::$cache_dir, '/') . '/';
-
-        if (! file_exists(self::$cache_dir)) {
-            if (! mkdir(self::$cache_dir)) {
-                throw new Exception('Cache directory couldn\'t be created: ' . self::$cache_dir);
+        if (! file_exists(self::$cacheDir)) {
+            if (! mkdir(self::$cacheDir)) {
+                throw new Exception('Cache directory couldn\'t be created: ' . self::$cacheDir);
             }
-        } elseif (! is_dir(self::$cache_dir)) {
-            throw new Exception('Cache directory doesn\'t exist: ' . self::$cache_dir);
-        } elseif (! is_writable(self::$cache_dir)) {
-            throw new Exception('Cache directory isn\'t writable: ' . self::$cache_dir);
+        } elseif (! is_dir(self::$cacheDir)) {
+            throw new Exception('Cache directory doesn\'t exist: ' . self::$cacheDir);
+        } elseif (! is_writable(self::$cacheDir)) {
+            throw new Exception('Cache directory isn\'t writable: ' . self::$cacheDir);
         }
     }
 
     /**
      * Delete unused cached files
-     *
      */
     public static function cleanCache()
     {
         static $clean = false;
 
-
-        if ($clean || empty(self::$cache_dir)) {
+        if ($clean || empty(self::$cacheDir)) {
             return;
         }
 
@@ -203,14 +202,16 @@ public static function cleanCache()
 
         // only remove files with extensions created by SCSSPHP Cache
         // css files removed based on the list files
-        $remove_types = array('scsscache' => 1);
+        $removeTypes = ['scsscache' => 1];
+
+        $files = scandir(self::$cacheDir);
 
-        $files = scandir(self::$cache_dir);
         if (! $files) {
             return;
         }
 
-        $check_time = time() - self::$gc_lifetime;
+        $checkTime = time() - self::$gcLifetime;
+
         foreach ($files as $file) {
             // don't delete if the file wasn't created with SCSSPHP Cache
             if (strpos($file, self::$prefix) !== 0) {
@@ -220,20 +221,19 @@ public static function cleanCache()
             $parts = explode('.', $file);
             $type = array_pop($parts);
 
-
-            if (! isset($remove_types[$type])) {
+            if (! isset($removeTypes[$type])) {
                 continue;
             }
 
-            $full_path = self::$cache_dir . $file;
-            $mtime = filemtime($full_path);
+            $fullPath = self::$cacheDir . $file;
+            $mtime = filemtime($fullPath);
 
             // don't delete if it's a relatively new file
-            if ($mtime > $check_time) {
+            if ($mtime > $checkTime) {
                 continue;
             }
 
-            unlink($full_path);
+            unlink($fullPath);
         }
     }
 }
diff --git a/src/Compiler.php b/src/Compiler.php
index 50785aac..d22d0a35 100644
--- a/src/Compiler.php
+++ b/src/Compiler.php
@@ -99,17 +99,17 @@ class Compiler
         'function' => '^',
     ];
 
-    static public $true = [Type::T_KEYWORD, 'true'];
-    static public $false = [Type::T_KEYWORD, 'false'];
-    static public $null = [Type::T_NULL];
-    static public $nullString = [Type::T_STRING, '', []];
+    static public $true         = [Type::T_KEYWORD, 'true'];
+    static public $false        = [Type::T_KEYWORD, 'false'];
+    static public $null         = [Type::T_NULL];
+    static public $nullString   = [Type::T_STRING, '', []];
     static public $defaultValue = [Type::T_KEYWORD, ''];
     static public $selfSelector = [Type::T_SELF];
-    static public $emptyList = [Type::T_LIST, '', []];
-    static public $emptyMap = [Type::T_MAP, [], []];
-    static public $emptyString = [Type::T_STRING, '"', []];
-    static public $with = [Type::T_KEYWORD, 'with'];
-    static public $without = [Type::T_KEYWORD, 'without'];
+    static public $emptyList    = [Type::T_LIST, '', []];
+    static public $emptyMap     = [Type::T_MAP, [], []];
+    static public $emptyString  = [Type::T_STRING, '"', []];
+    static public $with         = [Type::T_KEYWORD, 'with'];
+    static public $without      = [Type::T_KEYWORD, 'without'];
 
     protected $importPaths = [''];
     protected $importCache = [];
@@ -165,27 +165,28 @@ class Compiler
     /**
      * Constructor
      */
-    public function __construct($cache_options = null)
+    public function __construct($cacheOptions = null)
     {
         $this->parsedFiles = [];
         $this->sourceNames = [];
 
-        if ($cache_options) {
-            $this->cache = new Cache($cache_options);
+        if ($cacheOptions) {
+            $this->cache = new Cache($cacheOptions);
         }
     }
 
     public function getCompileOptions()
     {
-        $options = array(
-            'importPaths' => $this->importPaths,
-            'registeredVars' => $this->registeredVars,
+        $options = [
+            'importPaths'        => $this->importPaths,
+            'registeredVars'     => $this->registeredVars,
             'registeredFeatures' => $this->registeredFeatures,
-            'encoding' => $this->encoding,
-            'sourceMap' => serialize($this->sourceMap),
-            'sourceMapOptions' => $this->sourceMapOptions,
-            'formater' => $this->formatter,
-        );
+            'encoding'           => $this->encoding,
+            'sourceMap'          => serialize($this->sourceMap),
+            'sourceMapOptions'   => $this->sourceMapOptions,
+            'formatter'          => $this->formatter,
+        ];
+
         return $options;
     }
 
@@ -201,22 +202,25 @@ public function getCompileOptions()
      */
     public function compile($code, $path = null)
     {
-
         if ($this->cache) {
-            $cache_key = ($path ? $path : "(stdin)") . ":" . md5($code);
-            $compile_options = $this->getCompileOptions();
-            $cache = $this->cache->getCache("compile", $cache_key, $compile_options);
+            $cacheKey = ($path ? $path : "(stdin)") . ":" . md5($code);
+            $compileOptions = $this->getCompileOptions();
+            $cache = $this->cache->getCache("compile", $cacheKey, $compileOptions);
+
             if (is_array($cache)
-                and isset($cache['dependencies'])
-                and isset($cache['out']) ) {
+                && isset($cache['dependencies'])
+                && isset($cache['out'])
+            ) {
                 // check if any dependency file changed before accepting the cache
                 foreach ($cache['dependencies'] as $file => $mtime) {
-                    if (!file_exists($file)
-                        or filemtime($file) !== $mtime) {
+                    if (! file_exists($file)
+                        || filemtime($file) !== $mtime
+                    ) {
                         unset($cache);
                         break;
                     }
                 }
+
                 if (isset($cache)) {
                     return $cache['out'];
                 }
@@ -279,12 +283,13 @@ public function compile($code, $path = null)
             $out .= sprintf('/*# sourceMappingURL=%s */', $sourceMapUrl);
         }
 
-        if ($this->cache and isset($cache_key) and isset($compile_options)) {
-            $v = array(
+        if ($this->cache && isset($cacheKey) && isset($compileOptions)) {
+            $v = [
                 'dependencies' => $this->getParsedFiles(),
                 'out' => &$out,
-            );
-            $this->cache->setCache("compile", $cache_key, $v, $compile_options);
+            ];
+
+            $this->cache->setCache("compile", $cacheKey, $v, $compileOptions);
         }
 
         return $out;
@@ -490,6 +495,7 @@ protected function flattenSelectors(OutputBlock $block, $parentKey = null)
     protected function glueFunctionSelectors($parts)
     {
         $new = [];
+
         foreach ($parts as $part) {
             if (is_array($part)) {
                 $part = $this->glueFunctionSelectors($part);
@@ -506,6 +512,7 @@ protected function glueFunctionSelectors($parts)
                 }
             }
         }
+
         return $new;
     }
 
@@ -520,6 +527,7 @@ protected function glueFunctionSelectors($parts)
     protected function matchExtends($selector, &$out, $from = 0, $initial = true)
     {
         static $partsPile = [];
+
         $selector = $this->glueFunctionSelectors($selector);
 
         foreach ($selector as $i => $part) {
@@ -539,8 +547,8 @@ protected function matchExtends($selector, &$out, $from = 0, $initial = true)
 
             if ($this->matchExtendsSingle($part, $origin)) {
                 $partsPile[] = $part;
-                $after = array_slice($selector, $i + 1);
-                $before = array_slice($selector, 0, $i);
+                $after       = array_slice($selector, $i + 1);
+                $before      = array_slice($selector, 0, $i);
 
                 list($before, $nonBreakableBefore) = $this->extractRelationshipFromFragment($before);
 
@@ -548,7 +556,7 @@ protected function matchExtends($selector, &$out, $from = 0, $initial = true)
                     $k = 0;
 
                     // remove shared parts
-                    if (count($new)>1) {
+                    if (count($new) > 1) {
                         while ($k < $i && isset($new[$k]) && $selector[$k] === $new[$k]) {
                             $k++;
                         }
@@ -561,7 +569,7 @@ protected function matchExtends($selector, &$out, $from = 0, $initial = true)
                         $slice = [];
 
                         foreach ($tempReplacement[$l] as $chunk) {
-                            if (!in_array($chunk, $slice)) {
+                            if (! in_array($chunk, $slice)) {
                                 $slice[] = $chunk;
                             }
                         }
@@ -592,19 +600,19 @@ protected function matchExtends($selector, &$out, $from = 0, $initial = true)
                     $out[] = $result;
 
                     // recursively check for more matches
-                    $startRecursFrom = count($before) + min(count($nonBreakableBefore), count($mergedBefore));
-                    $this->matchExtends($result, $out, $startRecursFrom, false);
+                    $startRecurseFrom = count($before) + min(count($nonBreakableBefore), count($mergedBefore));
+                    $this->matchExtends($result, $out, $startRecurseFrom, false);
 
                     // selector sequence merging
                     if (! empty($before) && count($new) > 1) {
-                        $sharedParts = $k > 0 ? array_slice($before, 0, $k) : [];
+                        $preSharedParts = $k > 0 ? array_slice($before, 0, $k) : [];
                         $postSharedParts = $k > 0 ? array_slice($before, $k) : $before;
 
-                        list($injectBetweenSharedParts, $nonBreakable2) = $this->extractRelationshipFromFragment($afterBefore);
+                        list($betweenSharedParts, $nonBreakable2) = $this->extractRelationshipFromFragment($afterBefore);
 
                         $result2 = array_merge(
-                            $sharedParts,
-                            $injectBetweenSharedParts,
+                            $preSharedParts,
+                            $betweenSharedParts,
                             $postSharedParts,
                             $nonBreakable2,
                             $nonBreakableBefore,
@@ -615,6 +623,7 @@ protected function matchExtends($selector, &$out, $from = 0, $initial = true)
                         $out[] = $result2;
                     }
                 }
+
                 array_pop($partsPile);
             }
         }
@@ -671,6 +680,7 @@ protected function matchExtendsSingle($rawSingle, &$outOrigin)
 
         foreach ($counts as $idx => $count) {
             list($target, $origin, /* $block */) = $this->extends[$idx];
+
             $origin = $this->glueFunctionSelectors($origin);
 
             // check count
@@ -797,6 +807,7 @@ protected function compileMedia(Block $media)
         if (! empty($mediaQueries) && $mediaQueries) {
             $previousScope = $this->scope;
             $parentScope = $this->mediaParent($this->scope);
+
             foreach ($mediaQueries as $mediaQuery) {
                 $this->scope = $this->makeOutputBlock(Type::T_MEDIA, [$mediaQuery]);
 
@@ -811,9 +822,9 @@ protected function compileMedia(Block $media)
                 $type = $child[0];
 
                 if ($type !== Type::T_BLOCK &&
-                  $type !== Type::T_MEDIA &&
-                  $type !== Type::T_DIRECTIVE &&
-                  $type !== Type::T_IMPORT
+                    $type !== Type::T_MEDIA &&
+                    $type !== Type::T_DIRECTIVE &&
+                    $type !== Type::T_IMPORT
                 ) {
                     $needsWrap = true;
                     break;
@@ -1002,7 +1013,7 @@ protected function filterScopeWithout($scope, $without)
             }
         }
 
-        if (!count($filteredScopes)) {
+        if (! count($filteredScopes)) {
             return $this->rootBlock;
         }
 
@@ -1136,10 +1147,13 @@ protected function filterWithout($envs, $without)
 
         foreach ($envs as $e) {
             if ($e->block && $this->isWithout($without, $e->block)) {
-                continue;
+                $ec = clone $e;
+                $ec->block = null;
+                $ec->selectors = [];
+                $filtered[] = $ec;
+            } else {
+                $filtered[] = $e;
             }
-
-            $filtered[] = $e;
         }
 
         return $this->extractEnv($filtered);
@@ -1338,7 +1352,7 @@ protected function compileBlock(Block $block)
     protected function compileComment($block)
     {
         $out = $this->makeOutputBlock(Type::T_COMMENT);
-        $out->lines[] = $block[1];
+        $out->lines[] = is_string($block[1]) ? $block[1] : $this->compileValue($block[1]);
 
         $this->scope->children[] = $out;
     }
@@ -1413,8 +1427,8 @@ protected function evalSelectorPart($part)
     /**
      * Collapse selectors
      *
-     * @param array $selectors
-     * @param bool $selectorFormat
+     * @param array   $selectors
+     * @param boolean $selectorFormat
      *   if false return a collapsed string
      *   if true return an array description of a structured selector
      *
@@ -1427,6 +1441,7 @@ protected function collapseSelectors($selectors, $selectorFormat = false)
         foreach ($selectors as $selector) {
             $output = [];
             $glueNext = false;
+
             foreach ($selector as $node) {
                 $compound = '';
 
@@ -1436,6 +1451,7 @@ function ($value, $key) use (&$compound) {
                         $compound .= $value;
                     }
                 );
+
                 if ($selectorFormat && $this->isImmediateRelationshipCombinator($compound)) {
                     if (count($output)) {
                         $output[count($output) - 1] .= ' ' . $compound;
@@ -1459,6 +1475,7 @@ function ($value, $key) use (&$compound) {
             } else {
                 $output = implode(' ', $output);
             }
+
             $parts[] = $output;
         }
 
@@ -1489,6 +1506,7 @@ protected function revertSelfSelector($selectors)
                 }
             }
         }
+
         return $selectors;
     }
 
@@ -1604,6 +1622,7 @@ protected function pushCallStack($name = '')
           Parser::SOURCE_LINE => $this->sourceLine,
           Parser::SOURCE_COLUMN => $this->sourceColumn
         ];
+
         // infinite calling loop
         if (count($this->callStack) > 25000) {
             // not displayed but you can var_dump it to deep debug
@@ -1630,6 +1649,7 @@ protected function popCallStack()
     protected function compileChildren($stms, OutputBlock $out, $traceName = '')
     {
         $this->pushCallStack($traceName);
+
         foreach ($stms as $stm) {
             $ret = $this->compileChild($stm, $out);
 
@@ -1637,6 +1657,7 @@ protected function compileChildren($stms, OutputBlock $out, $traceName = '')
                 return $ret;
             }
         }
+
         $this->popCallStack();
 
         return null;
@@ -1655,6 +1676,7 @@ protected function compileChildren($stms, OutputBlock $out, $traceName = '')
     protected function compileChildrenNoReturn($stms, OutputBlock $out, $selfParent = null, $traceName = '')
     {
         $this->pushCallStack($traceName);
+
         foreach ($stms as $stm) {
             if ($selfParent && isset($stm[1]) && is_object($stm[1]) && $stm[1] instanceof Block) {
                 $stm[1]->selfParent = $selfParent;
@@ -1674,6 +1696,7 @@ protected function compileChildrenNoReturn($stms, OutputBlock $out, $selfParent
                 return;
             }
         }
+
         $this->popCallStack();
     }
 
@@ -1754,12 +1777,14 @@ protected function compileMediaQuery($queryList)
             $parts = [];
 
             $mediaTypeOnly = true;
+
             foreach ($query as $q) {
                 if ($q[0] !== Type::T_MEDIA_TYPE) {
                     $mediaTypeOnly = false;
                     break;
                 }
             }
+
             foreach ($query as $q) {
                 switch ($q[0]) {
                     case Type::T_MEDIA_TYPE:
@@ -1770,23 +1795,29 @@ protected function compileMediaQuery($queryList)
                                 if ($type) {
                                     array_unshift($parts, implode(' ', array_filter($type)));
                                 }
+
                                 if (! empty($parts)) {
                                     if (strlen($current)) {
                                         $current .= $this->formatter->tagSeparator;
                                     }
+
                                     $current .= implode(' and ', $parts);
                                 }
+
                                 if ($current) {
                                     $out[] = $start . $current;
                                 }
+
                                 $current = "";
                                 $type = null;
                                 $parts = [];
                             }
                         }
+
                         if ($newType === ['all'] && $default) {
                             $default = $start . 'all';
                         }
+
                         // all can be safely ignored and mixed with whatever else
                         if ($newType !== ['all']) {
                             if ($type) {
@@ -1840,10 +1871,12 @@ protected function compileMediaQuery($queryList)
         if ($current) {
             $out[] = $start . $current;
         }
+
         // no @media type except all, and no conflict?
-        if (!$out && $default) {
+        if (! $out && $default) {
             $out[] = $default;
         }
+
         return $out;
     }
 
@@ -1881,6 +1914,7 @@ protected function mergeDirectRelationships($selectors1, $selectors2)
                 } else {
                     $merged = array_merge($selectors1, [$part1], $selectors2, [$part2], $merged);
                 }
+
                 break;
             }
 
@@ -2018,11 +2052,11 @@ protected function compileChild($child, OutputBlock $out)
             $this->sourceIndex = isset($child[Parser::SOURCE_INDEX]) ? $child[Parser::SOURCE_INDEX] : null;
             $this->sourceLine = isset($child[Parser::SOURCE_LINE]) ? $child[Parser::SOURCE_LINE] : -1;
             $this->sourceColumn = isset($child[Parser::SOURCE_COLUMN]) ? $child[Parser::SOURCE_COLUMN] : -1;
-        } elseif (is_array($child) and isset($child[1]->sourceLine)) {
+        } elseif (is_array($child) && isset($child[1]->sourceLine)) {
             $this->sourceIndex = $child[1]->sourceIndex;
             $this->sourceLine = $child[1]->sourceLine;
             $this->sourceColumn = $child[1]->sourceColumn;
-        } elseif (! empty($out->sourceLine) and ! empty($out->sourceName)) {
+        } elseif (! empty($out->sourceLine) && ! empty($out->sourceName)) {
             $this->sourceLine = $out->sourceLine;
             $this->sourceIndex = array_search($out->sourceName, $this->sourceNames);
 
@@ -2379,7 +2413,8 @@ protected function compileChild($child, OutputBlock $out)
                 break;
 
             case Type::T_MIXIN_CONTENT:
-                $content = $this->get(static::$namespaces['special'] . 'content', false, isset($this->storeEnv) ? $this->storeEnv : $this->env);
+                $env = isset($this->storeEnv) ? $this->storeEnv : $this->env;
+                $content = $this->get(static::$namespaces['special'] . 'content', false, $env);
 
                 if (! $content) {
                     $content = new \stdClass();
@@ -2897,11 +2932,17 @@ protected function opAdd($left, $right)
      */
     protected function opAnd($left, $right, $shouldEval)
     {
+        $truthy = ($left === static::$null || $right === static::$null) ||
+                  ($left === static::$false || $left === static::$true) &&
+                  ($right === static::$false || $right === static::$true);
+
         if (! $shouldEval) {
-            return null;
+            if (! $truthy) {
+                return null;
+            }
         }
 
-        if ($left !== static::$false and $left !== static::$null) {
+        if ($left !== static::$false && $left !== static::$null) {
             return $this->reduce($right, true);
         }
 
@@ -2919,11 +2960,17 @@ protected function opAnd($left, $right, $shouldEval)
      */
     protected function opOr($left, $right, $shouldEval)
     {
+        $truthy = ($left === static::$null || $right === static::$null) ||
+                  ($left === static::$false || $left === static::$true) &&
+                  ($right === static::$false || $right === static::$true);
+
         if (! $shouldEval) {
-            return null;
+            if (! $truthy) {
+                return null;
+            }
         }
 
-        if ($left !== static::$false and $left !== static::$null) {
+        if ($left !== static::$false && $left !== static::$null) {
             return $left;
         }
 
@@ -3401,7 +3448,7 @@ protected function multiplySelectors(Environment $env, $selfParent = null)
 
         $selfParentSelectors = null;
 
-        if (!is_null($selfParent) and $selfParent->selectors) {
+        if (! is_null($selfParent) && $selfParent->selectors) {
             $selfParentSelectors = $this->evalSelectors($selfParent->selectors);
         }
 
@@ -3444,10 +3491,10 @@ protected function multiplySelectors(Environment $env, $selfParent = null)
     /**
      * Join selectors; looks for & to replace, or append parent before child
      *
-     * @param array $parent
-     * @param array $child
-     * @param bool  &$stillHasSelf
-     * @param array $selfParentSelectors
+     * @param array   $parent
+     * @param array   $child
+     * @param boolean &$stillHasSelf
+     * @param array   $selfParentSelectors
 
      * @return array
      */
@@ -3464,7 +3511,8 @@ protected function joinSelectors($parent, $child, &$stillHasSelf, $selfParentSel
                 if ($p === static::$selfSelector && $setSelf) {
                     $stillHasSelf = true;
                 }
-                if ($p === static::$selfSelector && !$setSelf) {
+
+                if ($p === static::$selfSelector && ! $setSelf) {
                     $setSelf = true;
 
                     if (is_null($selfParentSelectors)) {
@@ -3485,6 +3533,7 @@ protected function joinSelectors($parent, $child, &$stillHasSelf, $selfParentSel
                                 });
                                 $pp = implode($flatten);
                             }
+
                             $newPart[] = $pp;
                         }
                     }
@@ -3538,7 +3587,11 @@ protected function multiplyMedia(Environment $env = null, $childQueries = null)
 
             foreach ($parentQueries as $parentQuery) {
                 foreach ($originalQueries as $childQuery) {
-                    $childQueries []= array_merge($parentQuery, [[Type::T_MEDIA_TYPE, [Type::T_KEYWORD, 'all']]], $childQuery);
+                    $childQueries[] = array_merge(
+                        $parentQuery,
+                        [[Type::T_MEDIA_TYPE, [Type::T_KEYWORD, 'all']]],
+                        $childQuery
+                    );
                 }
             }
         }
@@ -3727,6 +3780,7 @@ public function get($name, $shouldThrow = true, Environment $env = null, $unredu
             if ($maxDepth-- <= 0) {
                 break;
             }
+
             if (array_key_exists($normalizedName, $env->store)) {
                 if ($unreduced && isset($env->storeUnreduced[$normalizedName])) {
                     return $env->storeUnreduced[$normalizedName];
@@ -4040,7 +4094,7 @@ public function findImport($url)
                 // check urls for normal import paths
                 foreach ($urls as $full) {
                     $separator = (
-                        !empty($dir) &&
+                        ! empty($dir) &&
                         substr($dir, -1) !== '/' &&
                         substr($full, 0, 1) !== '/'
                     ) ? '/' : '';
@@ -4108,17 +4162,21 @@ public function throwError($msg)
             return;
         }
 
+        $line   = $this->sourceLine;
+        $column = $this->sourceColumn;
+
+        $loc = isset($this->sourceNames[$this->sourceIndex])
+             ? $this->sourceNames[$this->sourceIndex] . " on line $line, at column $column"
+             : "line: $line, column: $column";
+
         if (func_num_args() > 1) {
             $msg = call_user_func_array('sprintf', func_get_args());
         }
 
-        $line = $this->sourceLine;
-        $loc = isset($this->sourceNames[$this->sourceIndex])
-             ? $this->sourceNames[$this->sourceIndex] . " on line $line"
-             : "line: $line";
         $msg = "$msg: $loc";
 
         $callStackMsg = $this->callStackMessage();
+
         if ($callStackMsg) {
             $msg .= "\nCall Stack:\n" . $callStackMsg;
         }
@@ -4127,8 +4185,11 @@ public function throwError($msg)
     }
 
     /**
-     * @param bool $all
-     * @param null $limit
+     * Beautify call stack for output
+     *
+     * @param boolean $all
+     * @param null    $limit
+     *
      * @return string
      */
     protected function callStackMessage($all = false, $limit = null)
@@ -4145,7 +4206,8 @@ protected function callStackMessage($all = false, $limit = null)
                           : '(unknown file)');
                     $msg .= " on line " . $call[Parser::SOURCE_LINE];
                     $callStackMsg[] = $msg;
-                    if (!is_null($limit) && $ncall>$limit) {
+
+                    if (! is_null($limit) && $ncall>$limit) {
                         break;
                     }
                 }
@@ -5974,4 +6036,624 @@ protected function libInspect($args)
 
         return $args[0];
     }
+
+    /**
+     * Preprocess selector args
+     *
+     * @param array $arg
+     *
+     * @return array|boolean
+     */
+    protected function getSelectorArg($arg)
+    {
+        static $parser = null;
+
+        if (is_null($parser)) {
+            $parser = $this->parserFactory(__METHOD__);
+        }
+
+        $arg = $this->libUnquote([$arg]);
+        $arg = $this->compileValue($arg);
+
+        $parsedSelector = [];
+
+        if ($parser->parseSelector($arg, $parsedSelector)) {
+            $selector = $this->evalSelectors($parsedSelector);
+            $gluedSelector = $this->glueFunctionSelectors($selector);
+
+            return $gluedSelector;
+        }
+
+        return false;
+    }
+
+    /**
+     * Postprocess selector to output in right format
+     *
+     * @param array $selectors
+     *
+     * @return string
+     */
+    protected function formatOutputSelector($selectors)
+    {
+        $selectors = $this->collapseSelectors($selectors, true);
+
+        return $selectors;
+    }
+
+    protected static $libIsSuperselector = ['super', 'sub'];
+    protected function libIsSuperselector($args)
+    {
+        list($super, $sub) = $args;
+
+        $super = $this->getSelectorArg($super);
+        $sub = $this->getSelectorArg($sub);
+
+        return $this->isSuperSelector($super, $sub);
+    }
+
+    /**
+     * Test a $super selector again $sub
+     *
+     * @param array $super
+     * @param array $sub
+     *
+     * @return boolean
+     */
+    protected function isSuperSelector($super, $sub)
+    {
+        // one and only one selector for each arg
+        if (! $super || count($super) !== 1) {
+            $this->throwError("Invalid super selector for isSuperSelector()");
+        }
+
+        if (! $sub || count($sub) !== 1) {
+            $this->throwError("Invalid sub selector for isSuperSelector()");
+        }
+
+        $super = reset($super);
+        $sub = reset($sub);
+
+        $i = 0;
+        $nextMustMatch = false;
+
+        foreach ($super as $node) {
+            $compound = '';
+
+            array_walk_recursive(
+                $node,
+                function ($value, $key) use (&$compound) {
+                    $compound .= $value;
+                }
+            );
+
+            if ($this->isImmediateRelationshipCombinator($compound)) {
+                if ($node !== $sub[$i]) {
+                    return false;
+                }
+
+                $nextMustMatch = true;
+                $i++;
+            } else {
+                while ($i < count($sub) && ! $this->isSuperPart($node, $sub[$i])) {
+                    if ($nextMustMatch) {
+                        return false;
+                    }
+
+                    $i++;
+                }
+
+                if ($i >= count($sub)) {
+                    return false;
+                }
+
+                $nextMustMatch = false;
+                $i++;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Test a part of super selector again a part of sub selector
+     *
+     * @param array $superParts
+     * @param array $subParts
+     *
+     * @return boolean
+     */
+    protected function isSuperPart($superParts, $subParts)
+    {
+        $i = 0;
+
+        foreach ($superParts as $superPart) {
+            while ($i < count($subParts) && $subParts[$i] !== $superPart) {
+                $i++;
+            }
+
+            if ($i >= count($subParts)) {
+                return false;
+            }
+
+            $i++;
+        }
+
+        return true;
+    }
+
+    //protected static $libSelectorAppend = ['selector...'];
+    protected function libSelectorAppend($args)
+    {
+        if (count($args) < 1) {
+            $this->throwError("selector-append() needs at least 1 argument");
+        }
+
+        $selectors = array_map([$this, 'getSelectorArg'], $args);
+
+        return $this->formatOutputSelector($this->selectorAppend($selectors));
+    }
+
+    /**
+     * Append parts of the last selector in the list to the previous, recursively
+     *
+     * @param array $selectors
+     *
+     * @return array
+     *
+     * @throws \Leafo\ScssPhp\Exception\CompilerException
+     */
+    protected function selectorAppend($selectors)
+    {
+        $lastSelectors = array_pop($selectors);
+
+        if (! $lastSelectors) {
+            $this->throwError("Invalid selector list in selector-append()");
+        }
+
+        while (count($selectors)) {
+            $previousSelectors = array_pop($selectors);
+
+            if (! $previousSelectors) {
+                $this->throwError("Invalid selector list in selector-append()");
+            }
+
+            // do the trick, happening $lastSelector to $previousSelector
+            $appended = [];
+
+            foreach ($lastSelectors as $lastSelector) {
+                $previous = $previousSelectors;
+
+                foreach ($lastSelector as $lastSelectorParts) {
+                    foreach ($lastSelectorParts as $lastSelectorPart) {
+                        foreach ($previous as $i => $previousSelector) {
+                            foreach ($previousSelector as $j => $previousSelectorParts) {
+                                $previous[$i][$j][] = $lastSelectorPart;
+                            }
+                        }
+                    }
+                }
+
+                foreach ($previous as $ps) {
+                    $appended[] = $ps;
+                }
+            }
+
+            $lastSelectors = $appended;
+        }
+
+        return $lastSelectors;
+    }
+
+    protected static $libSelectorExtend = ['selectors', 'extendee', 'extender'];
+    protected function libSelectorExtend($args)
+    {
+        list($selectors, $extendee, $extender) = $args;
+
+        $selectors = $this->getSelectorArg($selectors);
+        $extendee = $this->getSelectorArg($extendee);
+        $extender = $this->getSelectorArg($extender);
+
+        if (! $selectors || ! $extendee || ! $extender) {
+            $this->throwError("selector-extend() invalid arguments");
+        }
+
+        $extended = $this->extendOrReplaceSelectors($selectors, $extendee, $extender);
+
+        return $this->formatOutputSelector($extended);
+    }
+
+    protected static $libSelectorReplace = ['selectors', 'original', 'replacement'];
+    protected function libSelectorReplace($args)
+    {
+        list($selectors, $original, $replacement) = $args;
+
+        $selectors = $this->getSelectorArg($selectors);
+        $original = $this->getSelectorArg($original);
+        $replacement = $this->getSelectorArg($replacement);
+
+        if (! $selectors || ! $original || ! $replacement) {
+            $this->throwError("selector-replace() invalid arguments");
+        }
+
+        $replaced = $this->extendOrReplaceSelectors($selectors, $original, $replacement, true);
+
+        return $this->formatOutputSelector($replaced);
+    }
+
+    /**
+     * Extend/replace in selectors
+     * used by selector-extend and selector-replace that use the same logic
+     *
+     * @param array   $selectors
+     * @param array   $extendee
+     * @param array   $extender
+     * @param boolean $replace
+     *
+     * @return array
+     */
+    protected function extendOrReplaceSelectors($selectors, $extendee, $extender, $replace = false)
+    {
+        $saveExtends = $this->extends;
+        $saveExtendsMap = $this->extendsMap;
+
+        $this->extends = [];
+        $this->extendsMap = [];
+
+        foreach ($extendee as $es) {
+            // only use the first one
+            $this->pushExtends(reset($es), $extender, null);
+        }
+
+        $extended = [];
+
+        foreach ($selectors as $selector) {
+            if (! $replace) {
+                $extended[] = $selector;
+            }
+
+            $n = count($extended);
+
+            $this->matchExtends($selector, $extended);
+
+            // if didnt match, keep the original selector if we are in a replace operation
+            if ($replace and count($extended) === $n) {
+                $extended[] = $selector;
+            }
+        }
+
+        $this->extends = $saveExtends;
+        $this->extendsMap = $saveExtendsMap;
+
+        return $extended;
+    }
+
+    //protected static $libSelectorNest = ['selector...'];
+    protected function libSelectorNest($args)
+    {
+        if (count($args) < 1) {
+            $this->throwError("selector-nest() needs at least 1 argument");
+        }
+
+        $selectorsMap = array_map([$this, 'getSelectorArg'], $args);
+
+        $envs = [];
+        foreach ($selectorsMap as $selectors) {
+            $env = new Environment();
+            $env->selectors = $selectors;
+
+            $envs[] = $env;
+        }
+
+        $envs = array_reverse($envs);
+        $env = $this->extractEnv($envs);
+        $outputSelectors = $this->multiplySelectors($env);
+
+        return $this->formatOutputSelector($outputSelectors);
+    }
+
+    protected static $libSelectorParse = ['selectors'];
+    protected function libSelectorParse($args)
+    {
+        $selectors = reset($args);
+        $selectors = $this->getSelectorArg($selectors);
+
+        return $this->formatOutputSelector($selectors);
+    }
+
+    protected static $libSelectorUnify = ['selectors1', 'selectors2'];
+    protected function libSelectorUnify($args)
+    {
+        list($selectors1, $selectors2) = $args;
+
+        $selectors1 = $this->getSelectorArg($selectors1);
+        $selectors2 = $this->getSelectorArg($selectors2);
+
+        if (! $selectors1 || ! $selectors2) {
+            $this->throwError("selector-unify() invalid arguments");
+        }
+
+        // only consider the first compound of each
+        $compound1 = reset($selectors1);
+        $compound2 = reset($selectors2);
+
+        // unify them and that's it
+        $unified = $this->unifyCompoundSelectors($compound1, $compound2);
+
+        return $this->formatOutputSelector($unified);
+    }
+
+    /**
+     * The selector-unify magic as its best
+     * (at least works as expected on test cases)
+     *
+     * @param array $compound1
+     * @param array $compound2
+     * @return array|mixed
+     */
+    protected function unifyCompoundSelectors($compound1, $compound2)
+    {
+        if (! count($compound1)) {
+            return $compound2;
+        }
+
+        if (! count($compound2)) {
+            return $compound1;
+        }
+
+        // check that last part are compatible
+        $lastPart1 = array_pop($compound1);
+        $lastPart2 = array_pop($compound2);
+        $last = $this->mergeParts($lastPart1, $lastPart2);
+
+        if (! $last) {
+            return [[]];
+        }
+
+        $unifiedCompound = [$last];
+        $unifiedSelectors = [$unifiedCompound];
+
+        // do the rest
+        while (count($compound1) || count($compound2)) {
+            $part1 = end($compound1);
+            $part2 = end($compound2);
+
+            if ($part1 && ($match2 = $this->matchPartInCompound($part1, $compound2))) {
+                list($compound2, $part2, $after2) = $match2;
+
+                if ($after2) {
+                    $unifiedSelectors = $this->prependSelectors($unifiedSelectors, $after2);
+                }
+
+                $c = $this->mergeParts($part1, $part2);
+                $unifiedSelectors = $this->prependSelectors($unifiedSelectors, [$c]);
+                $part1 = $part2 = null;
+
+                array_pop($compound1);
+            }
+
+            if ($part2 && ($match1 = $this->matchPartInCompound($part2, $compound1))) {
+                list($compound1, $part1, $after1) = $match1;
+
+                if ($after1) {
+                    $unifiedSelectors = $this->prependSelectors($unifiedSelectors, $after1);
+                }
+
+                $c = $this->mergeParts($part2, $part1);
+                $unifiedSelectors = $this->prependSelectors($unifiedSelectors, [$c]);
+                $part1 = $part2 = null;
+
+                array_pop($compound2);
+            }
+
+            $new = [];
+
+            if ($part1 && $part2) {
+                array_pop($compound1);
+                array_pop($compound2);
+
+                $s = $this->prependSelectors($unifiedSelectors, [$part2]);
+                $new = array_merge($new, $this->prependSelectors($s, [$part1]));
+                $s = $this->prependSelectors($unifiedSelectors, [$part1]);
+                $new = array_merge($new, $this->prependSelectors($s, [$part2]));
+            } elseif ($part1) {
+                array_pop($compound1);
+
+                $new = array_merge($new, $this->prependSelectors($unifiedSelectors, [$part1]));
+            } elseif ($part2) {
+                array_pop($compound2);
+
+                $new = array_merge($new, $this->prependSelectors($unifiedSelectors, [$part2]));
+            }
+
+            if ($new) {
+                $unifiedSelectors = $new;
+            }
+        }
+
+        return $unifiedSelectors;
+    }
+
+    /**
+     * Prepend each selector from $selectors with $parts
+     *
+     * @param array $selectors
+     * @param array $parts
+     *
+     * @return array
+     */
+    protected function prependSelectors($selectors, $parts)
+    {
+        $new = [];
+
+        foreach ($selectors as $compoundSelector) {
+            array_unshift($compoundSelector, $parts);
+
+            $new[] = $compoundSelector;
+        }
+
+        return $new;
+    }
+
+    /**
+     * Try to find a matching part in a compound:
+     * - with same html tag name
+     * - with some class or id or something in common
+     *
+     * @param array $part
+     * @param array $compound
+     *
+     * @return array|boolean
+     */
+    protected function matchPartInCompound($part, $compound)
+    {
+        $partTag = $this->findTagName($part);
+        $before = $compound;
+        $after = [];
+
+        // try to find a match by tag name first
+        while (count($before)) {
+            $p = array_pop($before);
+
+            if ($partTag && $partTag !== '*' && $partTag == $this->findTagName($p)) {
+                return [$before, $p, $after];
+            }
+
+            $after[] = $p;
+        }
+
+        // try again matching a non empty intersection and a compatible tagname
+        $before = $compound;
+        $after = [];
+
+        while (count($before)) {
+            $p = array_pop($before);
+
+            if ($this->checkCompatibleTags($partTag, $this->findTagName($p))) {
+                if (count(array_intersect($part, $p))) {
+                    return [$before, $p, $after];
+                }
+            }
+
+            $after[] = $p;
+        }
+
+        return false;
+    }
+
+    /**
+     * Merge two part list taking care that
+     * - the html tag is coming first - if any
+     * - the :something are coming last
+     *
+     * @param array $parts1
+     * @param array $parts2
+     *
+     * @return array
+     */
+    protected function mergeParts($parts1, $parts2)
+    {
+        $tag1 = $this->findTagName($parts1);
+        $tag2 = $this->findTagName($parts2);
+        $tag = $this->checkCompatibleTags($tag1, $tag2);
+
+        // not compatible tags
+        if ($tag === false) {
+            return [];
+        }
+
+        if ($tag) {
+            if ($tag1) {
+                $parts1 = array_diff($parts1, [$tag1]);
+            }
+
+            if ($tag2) {
+                $parts2 = array_diff($parts2, [$tag2]);
+            }
+        }
+
+        $mergedParts = array_merge($parts1, $parts2);
+        $mergedOrderedParts = [];
+
+        foreach ($mergedParts as $part) {
+            if (strpos($part, ':') === 0) {
+                $mergedOrderedParts[] = $part;
+            }
+        }
+
+        $mergedParts = array_diff($mergedParts, $mergedOrderedParts);
+        $mergedParts = array_merge($mergedParts, $mergedOrderedParts);
+
+        if ($tag) {
+            array_unshift($mergedParts, $tag);
+        }
+
+        return $mergedParts;
+    }
+
+    /**
+     * Check the compatibility between two tag names:
+     * if both are defined they should be identical or one has to be '*'
+     *
+     * @param string $tag1
+     * @param string $tag2
+     *
+     * @return array|boolean
+     */
+    protected function checkCompatibleTags($tag1, $tag2)
+    {
+        $tags = [$tag1, $tag2];
+        $tags = array_unique($tags);
+        $tags = array_filter($tags);
+
+        if (count($tags)>1) {
+            $tags = array_diff($tags, ['*']);
+        }
+
+        // not compatible nodes
+        if (count($tags)>1) {
+            return false;
+        }
+
+        return $tags;
+    }
+
+    /**
+     * Find the html tag name in a selector parts list
+     *
+     * @param array $parts
+     *
+     * @return mixed|string
+     */
+    protected function findTagName($parts)
+    {
+        foreach ($parts as $part) {
+            if (! preg_match('/^[\[.:#%_-]/', $part)) {
+                return $part;
+            }
+        }
+
+        return '';
+    }
+
+    protected static $libSimpleSelectors = ['selector'];
+    protected function libSimpleSelectors($args)
+    {
+        $selector = reset($args);
+        $selector = $this->getSelectorArg($selector);
+
+        // remove selectors list layer, keeping the first one
+        $selector = reset($selector);
+
+        // remove parts list layer, keeping the first part
+        $part = reset($selector);
+
+        $listParts = [];
+
+        foreach ($part as $p) {
+            $listParts[] = [Type::T_STRING, '', [$p]];
+        }
+
+        return [Type::T_LIST, ',', $listParts];
+    }
 }
diff --git a/src/Formatter/Compressed.php b/src/Formatter/Compressed.php
index 52410b6c..ab38529d 100644
--- a/src/Formatter/Compressed.php
+++ b/src/Formatter/Compressed.php
@@ -69,8 +69,13 @@ protected function blockSelectors(OutputBlock $block)
     {
         $inner = $this->indentStr();
 
-        $this->write($inner
-            . implode($this->tagSeparator, str_replace(array(' > ', ' + ', ' ~ '), array('>', '+', '~'), $block->selectors))
-            . $this->open . $this->break);
+        $this->write(
+            $inner
+            . implode(
+                $this->tagSeparator,
+                str_replace([' > ', ' + ', ' ~ '], ['>', '+', '~'], $block->selectors)
+            )
+            . $this->open . $this->break
+        );
     }
 }
diff --git a/src/Formatter/Crunched.php b/src/Formatter/Crunched.php
index 31970255..da740ccd 100644
--- a/src/Formatter/Crunched.php
+++ b/src/Formatter/Crunched.php
@@ -67,8 +67,13 @@ protected function blockSelectors(OutputBlock $block)
     {
         $inner = $this->indentStr();
 
-        $this->write($inner
-            . implode($this->tagSeparator, str_replace(array(' > ', ' + ', ' ~ '), array('>', '+', '~'), $block->selectors))
-            . $this->open . $this->break);
+        $this->write(
+            $inner
+            . implode(
+                $this->tagSeparator,
+                str_replace([' > ', ' + ', ' ~ '], ['>', '+', '~'], $block->selectors)
+            )
+            . $this->open . $this->break
+        );
     }
 }
diff --git a/src/Parser.php b/src/Parser.php
index eb264bce..c05e4ee8 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -12,6 +12,7 @@
 namespace Leafo\ScssPhp;
 
 use Leafo\ScssPhp\Block;
+use Leafo\ScssPhp\Cache;
 use Leafo\ScssPhp\Compiler;
 use Leafo\ScssPhp\Exception\ParserException;
 use Leafo\ScssPhp\Node;
@@ -74,10 +75,10 @@ class Parser
      *
      * @api
      *
-     * @param string  $sourceName
-     * @param integer $sourceIndex
-     * @param string  $encoding
-     * @param Cache $cache
+     * @param string               $sourceName
+     * @param integer              $sourceIndex
+     * @param string               $encoding
+     * @param \Leafo\ScssPhp\Cache $cache
      */
     public function __construct($sourceName, $sourceIndex = 0, $encoding = 'utf-8', $cache = null)
     {
@@ -86,7 +87,7 @@ public function __construct($sourceName, $sourceIndex = 0, $encoding = 'utf-8',
         $this->charset          = null;
         $this->utf8             = ! $encoding || strtolower($encoding) === 'utf-8';
         $this->patternModifiers = $this->utf8 ? 'Aisu' : 'Ais';
-        $this->commentsSeen   = [];
+        $this->commentsSeen     = [];
 
         if (empty(static::$operatorPattern)) {
             static::$operatorPattern = '([*\/%+-]|[!=]\=|\>\=?|\<\=\>|\<\=?|and|or)';
@@ -129,9 +130,11 @@ public function getSourceName()
      */
     public function throwParseError($msg = 'parse error')
     {
-        list($line, /* $column */) = $this->getSourcePosition($this->count);
+        list($line, $column) = $this->getSourcePosition($this->count);
 
-        $loc = empty($this->sourceName) ? "line: $line" : "$this->sourceName on line $line";
+        $loc = empty($this->sourceName)
+             ? "line: $line, column: $column"
+             : "$this->sourceName on line $line, at column $column";
 
         if ($this->peek("(.*?)(\n|$)", $m, $this->count)) {
             throw new ParserException("$msg: failed at `$m[1]` $loc");
@@ -151,15 +154,15 @@ public function throwParseError($msg = 'parse error')
      */
     public function parse($buffer)
     {
-
         if ($this->cache) {
-            $cache_key = $this->sourceName . ":" . md5($buffer);
-            $parse_options = array(
+            $cacheKey = $this->sourceName . ":" . md5($buffer);
+            $parseOptions = [
                 'charset' => $this->charset,
                 'utf8' => $this->utf8,
-            );
-            $v = $this->cache->getCache("parse", $cache_key, $parse_options);
-            if (!is_null($v)) {
+            ];
+            $v = $this->cache->getCache("parse", $cacheKey, $parseOptions);
+
+            if (! is_null($v)) {
                 return $v;
             }
         }
@@ -199,12 +202,10 @@ public function parse($buffer)
             array_unshift($this->env->children, $this->charset);
         }
 
-        $this->env->isRoot    = true;
-
         $this->restoreEncoding();
 
         if ($this->cache) {
-            $this->cache->setCache("parse", $cache_key, $this->env, $parse_options);
+            $this->cache->setCache("parse", $cacheKey, $this->env, $parseOptions);
         }
 
         return $this->env;
@@ -661,9 +662,14 @@ protected function parseChunk()
         }
 
         // opening css block
-        if ($this->selectors($selectors) && $this->matchChar('{')) {
+        if ($this->selectors($selectors) && $this->matchChar('{', false)) {
             $this->pushBlock($selectors, $s);
 
+            if ($this->eatWhiteDefault) {
+                $this->whitespace();
+                $this->append(null); // collect comments at the begining if needed
+            }
+
             return true;
         }
 
@@ -674,6 +680,10 @@ protected function parseChunk()
             $foundSomething = false;
 
             if ($this->valueList($value)) {
+                if (empty($this->env->parent)) {
+                    $this->throwParseError('expected "{"');
+                }
+
                 $this->append([Type::T_ASSIGN, $name, $value], $s);
                 $foundSomething = true;
             }
@@ -932,6 +942,7 @@ protected function matchChar($char, $eatWhitespace = null)
         if ($eatWhitespace) {
             $this->whitespace();
         }
+
         return true;
     }
 
@@ -946,7 +957,6 @@ protected function matchChar($char, $eatWhitespace = null)
      */
     protected function literal($what, $len, $eatWhitespace = null)
     {
-
         if (strcasecmp(substr($this->buffer, $this->count, $len), $what) !== 0) {
             return false;
         }
@@ -960,6 +970,7 @@ protected function literal($what, $len, $eatWhitespace = null)
         if ($eatWhitespace) {
             $this->whitespace();
         }
+
         return true;
     }
 
@@ -974,12 +985,57 @@ protected function whitespace()
 
         while (preg_match(static::$whitePattern, $this->buffer, $m, null, $this->count)) {
             if (isset($m[1]) && empty($this->commentsSeen[$this->count])) {
-                $this->appendComment([Type::T_COMMENT, $m[1]]);
+                // comment that are kept in the output CSS
+                $comment = [];
+                $endCommentCount = $this->count + strlen($m[1]);
+
+                // find interpolations in comment
+                $p = strpos($this->buffer, '#{', $this->count);
+
+                while ($p !== false && $p < $endCommentCount) {
+                    $c = substr($this->buffer, $this->count, $p - $this->count);
+                    $comment[] = $c;
+                    $this->count = $p;
+                    $out = null;
+
+                    if ($this->interpolation($out)) {
+                        // keep right spaces in the following string part
+                        if ($out[3]) {
+                            while ($this->buffer[$this->count-1] !== '}') {
+                                $this->count--;
+                            }
+
+                            $out[3] = '';
+                        }
+
+                        $comment[] = $out;
+                    } else {
+                        $comment[] = substr($this->buffer, $this->count, 2);
+
+                        $this->count += 2;
+                    }
+
+                    $p = strpos($this->buffer, '#{', $this->count);
+                }
+
+                // remaining part
+                $c = substr($this->buffer, $this->count, $endCommentCount - $this->count);
+
+                if (! $comment) {
+                    // single part static comment
+                    $this->appendComment([Type::T_COMMENT, $c]);
+                } else {
+                    $comment[] = $c;
+                    $this->appendComment([Type::T_COMMENT, [Type::T_STRING, '', $comment]]);
+                }
 
                 $this->commentsSeen[$this->count] = true;
+                $this->count = $endCommentCount;
+            } else {
+                // comment that are ignored and not kept in the output css
+                $this->count += strlen($m[0]);
             }
 
-            $this->count += strlen($m[0]);
             $gotWhite = true;
         }
 
@@ -993,7 +1049,9 @@ protected function whitespace()
      */
     protected function appendComment($comment)
     {
-        $comment[1] = substr(preg_replace(['/^\s+/m', '/^(.)/m'], ['', ' \1'], $comment[1]), 1);
+        if ($comment[0] === Type::T_COMMENT && is_string($comment[1])) {
+            $comment[1] = substr(preg_replace(['/^\s+/m', '/^(.)/m'], ['', ' \1'], $comment[1]), 1);
+        }
 
         $this->env->comments[] = $comment;
     }
@@ -1006,15 +1064,17 @@ protected function appendComment($comment)
      */
     protected function append($statement, $pos = null)
     {
-        if ($pos !== null) {
-            list($line, $column) = $this->getSourcePosition($pos);
+        if (! is_null($statement)) {
+            if ($pos !== null) {
+                list($line, $column) = $this->getSourcePosition($pos);
 
-            $statement[static::SOURCE_LINE]   = $line;
-            $statement[static::SOURCE_COLUMN] = $column;
-            $statement[static::SOURCE_INDEX]  = $this->sourceIndex;
-        }
+                $statement[static::SOURCE_LINE]   = $line;
+                $statement[static::SOURCE_COLUMN] = $column;
+                $statement[static::SOURCE_INDEX]  = $this->sourceIndex;
+            }
 
-        $this->env->children[] = $statement;
+            $this->env->children[] = $statement;
+        }
 
         $comments = $this->env->comments;
 
@@ -1235,7 +1295,7 @@ protected function genericList(&$out, $parseItem, $delim = '', $flatten = true)
             }
         }
 
-        if (!$items) {
+        if (! $items) {
             $this->seek($s);
 
             return false;
@@ -1270,7 +1330,11 @@ protected function expression(&$out)
         }
 
         if ($this->matchChar('[')) {
-            if ($this->parenExpression($out, $s, "]")) {
+            if ($this->parenExpression($out, $s, "]", [Type::T_LIST, Type::T_KEYWORD])) {
+                if ($out[0] !== Type::T_LIST && $out[0] !== Type::T_MAP) {
+                    $out = [Type::T_STRING, '', [ '[', $out, ']' ]];
+                }
+
                 return true;
             }
 
@@ -1292,10 +1356,11 @@ protected function expression(&$out)
      * @param array   $out
      * @param integer $s
      * @param string  $closingParen
+     * @param array   $allowedTypes
      *
      * @return boolean
      */
-    protected function parenExpression(&$out, $s, $closingParen = ")")
+    protected function parenExpression(&$out, $s, $closingParen = ")", $allowedTypes = [Type::T_LIST, Type::T_MAP])
     {
         if ($this->matchChar($closingParen)) {
             $out = [Type::T_LIST, '', []];
@@ -1303,13 +1368,13 @@ protected function parenExpression(&$out, $s, $closingParen = ")")
             return true;
         }
 
-        if ($this->valueList($out) && $this->matchChar($closingParen) && $out[0] === Type::T_LIST) {
+        if ($this->valueList($out) && $this->matchChar($closingParen) && in_array($out[0], $allowedTypes)) {
             return true;
         }
 
         $this->seek($s);
 
-        if ($this->map($out)) {
+        if (in_array(Type::T_MAP, $allowedTypes) && $this->map($out)) {
             return true;
         }
 
@@ -1384,7 +1449,11 @@ protected function value(&$out)
         $char = $this->buffer[$this->count];
 
         if ($this->literal('url(', 4) && $this->match('data:([a-z]+)\/([a-z0-9.+-]+);base64,', $m, false)) {
-            $len = strspn($this->buffer, 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwyxz0123456789+/=', $this->count);
+            $len = strspn(
+                $this->buffer,
+                'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwyxz0123456789+/=',
+                $this->count
+            );
 
             $this->count += $len;
 
@@ -1398,6 +1467,19 @@ protected function value(&$out)
 
         $this->seek($s);
 
+        if ($this->literal('url(', 4, false) && $this->match('\s*(\/\/\S+)\s*', $m)) {
+            $content = 'url(' . $m[1];
+
+            if ($this->matchChar(')')) {
+                $content .= ')';
+                $out = [Type::T_KEYWORD, $content];
+
+                return true;
+            }
+        }
+
+        $this->seek($s);
+
         // not
         if ($char === 'n' && $this->literal('not', 3, false)) {
             if ($this->whitespace() && $this->value($inner)) {
@@ -1423,6 +1505,7 @@ protected function value(&$out)
 
             if ($this->value($inner)) {
                 $out = [Type::T_UNARY, '+', $inner, $this->inParens];
+
                 return true;
             }
 
@@ -1437,8 +1520,10 @@ protected function value(&$out)
 
             if ($this->variable($inner) || $this->unit($inner) || $this->parenValue($inner)) {
                 $out = [Type::T_UNARY, '-', $inner, $this->inParens];
+
                 return true;
             }
+
             $this->count--;
         }
 
@@ -1455,6 +1540,7 @@ protected function value(&$out)
 
         if ($this->matchChar('&', true)) {
             $out = [Type::T_SELF];
+
             return true;
         }
 
@@ -1474,6 +1560,12 @@ protected function value(&$out)
             return true;
         }
 
+        // unicode range with wildcards
+        if ($this->literal('U+', 2) && $this->match('([0-9A-F]+\?*)(-([0-9A-F]+))?', $m, false)) {
+            $out = [Type::T_KEYWORD, 'U+' . $m[0]];
+            return true;
+        }
+
         if ($this->keyword($keyword, false)) {
             if ($this->func($keyword, $out)) {
                 return true;
@@ -1642,7 +1734,7 @@ protected function argumentList(&$out)
             $args[] = [Type::T_STRING, '', [', ']];
         }
 
-        if (! $this->matchChar(')') || !$args) {
+        if (! $this->matchChar(')') || ! $args) {
             $this->seek($s);
 
             return false;
@@ -1740,7 +1832,7 @@ protected function map(&$out)
             }
         }
 
-        if (!$keys || ! $this->matchChar(')')) {
+        if (! $keys || ! $this->matchChar(')')) {
             $this->seek($s);
 
             return false;
@@ -1778,6 +1870,7 @@ protected function color(&$out)
                         $color[$i] = $t << 4 | $t;
                         $num >>= 4;
                     }
+
                     break;
 
                 case 6:
@@ -1788,6 +1881,7 @@ protected function color(&$out)
                         $color[$i] = $num & 0xff;
                         $num >>= 8;
                     }
+
                     break;
 
                 default:
@@ -1884,6 +1978,11 @@ protected function string(&$out)
                     $content[] = $m[2] . "'";
                 } elseif ($this->literal("\\", 1, false)) {
                     $content[] = $m[2] . "\\";
+                } elseif ($this->literal("\r\n", 2, false)
+                  || $this->matchChar("\r", false)
+                  || $this->matchChar("\n", false)
+                  || $this->matchChar("\f", false)) {
+                    // this is a continuation escaping, to be ignored
                 } else {
                     $content[] = $m[2];
                 }
@@ -1950,7 +2049,7 @@ protected function mixedKeyword(&$out)
 
         $this->eatWhiteDefault = $oldWhite;
 
-        if (!$parts) {
+        if (! $parts) {
             return false;
         }
 
@@ -2016,7 +2115,7 @@ protected function openString($end, &$out, $nestingOpen = null)
 
         $this->eatWhiteDefault = $oldWhite;
 
-        if (!$content) {
+        if (! $content) {
             return false;
         }
 
@@ -2058,6 +2157,7 @@ protected function interpolation(&$out, $lookWhite = true)
 
                 $out = [Type::T_INTERPOLATE, $value, $left, $right];
             }
+
             $this->eatWhiteDefault = $oldWhite;
 
             if ($this->eatWhiteDefault) {
@@ -2099,7 +2199,7 @@ protected function propertyName(&$out)
                 continue;
             }
 
-            if (!$parts && $this->match('[:.#]', $m, false)) {
+            if (! $parts && $this->match('[:.#]', $m, false)) {
                 // css hacks
                 $parts[] = $m[0];
                 continue;
@@ -2110,7 +2210,7 @@ protected function propertyName(&$out)
 
         $this->eatWhiteDefault = $oldWhite;
 
-        if (!$parts) {
+        if (! $parts) {
             return false;
         }
 
@@ -2142,24 +2242,24 @@ protected function propertyName(&$out)
      *
      * @return boolean
      */
-    protected function selectors(&$out)
+    protected function selectors(&$out, $subSelector = false)
     {
         $s = $this->count;
         $selectors = [];
 
-        while ($this->selector($sel)) {
+        while ($this->selector($sel, $subSelector)) {
             $selectors[] = $sel;
 
-            if (! $this->matchChar(',')) {
+            if (! $this->matchChar(',', true)) {
                 break;
             }
 
-            while ($this->matchChar(',')) {
+            while ($this->matchChar(',', true)) {
                 ; // ignore extra
             }
         }
 
-        if (!$selectors) {
+        if (! $selectors) {
             $this->seek($s);
 
             return false;
@@ -2177,23 +2277,23 @@ protected function selectors(&$out)
      *
      * @return boolean
      */
-    protected function selector(&$out)
+    protected function selector(&$out, $subSelector = false)
     {
         $selector = [];
 
         for (;;) {
-            if ($this->match('[>+~]+', $m)) {
+            if ($this->match('[>+~]+', $m, true)) {
                 $selector[] = [$m[0]];
                 continue;
             }
 
-            if ($this->selectorSingle($part)) {
+            if ($this->selectorSingle($part, $subSelector)) {
                 $selector[] = $part;
                 $this->match('\s+', $m);
                 continue;
             }
 
-            if ($this->match('\/[^\/]+\/', $m)) {
+            if ($this->match('\/[^\/]+\/', $m, true)) {
                 $selector[] = [$m[0]];
                 continue;
             }
@@ -2201,11 +2301,12 @@ protected function selector(&$out)
             break;
         }
 
-        if (!$selector) {
+        if (! $selector) {
             return false;
         }
 
         $out = $selector;
+
         return true;
     }
 
@@ -2220,7 +2321,7 @@ protected function selector(&$out)
      *
      * @return boolean
      */
-    protected function selectorSingle(&$out)
+    protected function selectorSingle(&$out, $subSelector = false)
     {
         $oldWhite = $this->eatWhiteDefault;
         $this->eatWhiteDefault = false;
@@ -2244,16 +2345,23 @@ protected function selectorSingle(&$out)
                 break;
             }
 
+            // parsing a sub selector in () stop with the closing )
+            if ($subSelector && $char === ')') {
+                break;
+            }
+
             //self
             switch ($char) {
                 case '&':
                     $parts[] = Compiler::$selfSelector;
                     $this->count++;
                     continue 2;
+
                 case '.':
                     $parts[] = '.';
                     $this->count++;
                     continue 2;
+
                 case '|':
                     $parts[] = '|';
                     $this->count++;
@@ -2307,19 +2415,48 @@ protected function selectorSingle(&$out)
 
                     $ss = $this->count;
 
-                    if ($this->matchChar('(') &&
-                      ($this->openString(')', $str, '(') || true) &&
-                      $this->matchChar(')')
+                    if ($nameParts === ['not'] || $nameParts === ['is'] ||
+                        $nameParts === ['has'] || $nameParts === ['where']
                     ) {
-                        $parts[] = '(';
-
-                        if (! empty($str)) {
-                            $parts[] = $str;
+                        if ($this->matchChar('(') &&
+                          ($this->selectors($subs, true) || true) &&
+                          $this->matchChar(')')
+                        ) {
+                            $parts[] = '(';
+
+                            while ($sub = array_shift($subs)) {
+                                while ($ps = array_shift($sub)) {
+                                    foreach ($ps as &$p) {
+                                        $parts[] = $p;
+                                    }
+                                    if (count($sub) && reset($sub)) {
+                                        $parts[] = ' ';
+                                    }
+                                }
+                                if (count($subs) && reset($subs)) {
+                                    $parts[] = ', ';
+                                }
+                            }
+
+                            $parts[] = ')';
+                        } else {
+                            $this->seek($ss);
                         }
-
-                        $parts[] = ')';
                     } else {
-                        $this->seek($ss);
+                        if ($this->matchChar('(') &&
+                          ($this->openString(')', $str, '(') || true) &&
+                          $this->matchChar(')')
+                        ) {
+                            $parts[] = '(';
+
+                            if (! empty($str)) {
+                                $parts[] = $str;
+                            }
+
+                            $parts[] = ')';
+                        } else {
+                            $this->seek($ss);
+                        }
                     }
 
                     continue;
@@ -2330,9 +2467,9 @@ protected function selectorSingle(&$out)
 
             // attribute selector
             if ($char === '[' &&
-              $this->matchChar('[') &&
-              ($this->openString(']', $str, '[') || true) &&
-              $this->matchChar(']')
+                $this->matchChar('[') &&
+                ($this->openString(']', $str, '[') || true) &&
+                $this->matchChar(']')
             ) {
                 $parts[] = '[';
 
@@ -2341,7 +2478,6 @@ protected function selectorSingle(&$out)
                 }
 
                 $parts[] = ']';
-
                 continue;
             }
 
@@ -2363,7 +2499,7 @@ protected function selectorSingle(&$out)
 
         $this->eatWhiteDefault = $oldWhite;
 
-        if (!$parts) {
+        if (! $parts) {
             return false;
         }
 
@@ -2406,7 +2542,7 @@ protected function keyword(&$word, $eatWhitespace = null)
     {
         if ($this->match(
             $this->utf8
-                ? '(([\pL\w_\-\*!"\']|[\\\\].)([\pL\w\-_"\']|[\\\\].)*)'
+                ? '(([\pL\w\x{00A0}-\x{10FFFF}_\-\*!"\']|[\\\\].)([\pL\w\x{00A0}-\x{10FFFF}\-_"\']|[\\\\].)*)'
                 : '(([\w_\-\*!"\']|[\\\\].)([\w\-_"\']|[\\\\].)*)',
             $m,
             $eatWhitespace
diff --git a/src/SourceMap/SourceMapGenerator.php b/src/SourceMap/SourceMapGenerator.php
index d2001462..fb11a0bf 100644
--- a/src/SourceMap/SourceMapGenerator.php
+++ b/src/SourceMap/SourceMapGenerator.php
@@ -137,7 +137,9 @@ public function saveMap($content)
         // directory does not exist
         if (! is_dir($dir)) {
             // FIXME: create the dir automatically?
-            throw new CompilerException(sprintf('The directory "%s" does not exist. Cannot save the source map.', $dir));
+            throw new CompilerException(
+                sprintf('The directory "%s" does not exist. Cannot save the source map.', $dir)
+            );
         }
 
         // FIXME: proper saving, with dir write check!
diff --git a/src/Version.php b/src/Version.php
index 19a6a02c..fe163a78 100644
--- a/src/Version.php
+++ b/src/Version.php
@@ -18,5 +18,5 @@
  */
 class Version
 {
-    const VERSION = 'v0.8.2';
+    const VERSION = 'v0.8.4';
 }
diff --git a/tests/FailingTest.php b/tests/FailingTest.php
index 86865049..95f693b2 100644
--- a/tests/FailingTest.php
+++ b/tests/FailingTest.php
@@ -62,56 +62,6 @@ public function provideFailing()
     {
         // @codingStandardsIgnoreStart
         return array(
-            array(
-                '#67 - weird @extend behavior', <<<'END_OF_SCSS'
-.nav-bar {
-    background: #eee;
-    > .item {
-        margin: 0 10px;
-    }
-}
-
-
-header ul {
-    @extend .nav-bar;
-    > li {
-        @extend .item;
-    }
-}
-END_OF_SCSS
-                , <<<END_OF_EXPECTED
-.nav-bar, header ul {
-  background: #eee; }
-  .nav-bar > .item, header ul > .item, header ul > li {
-    margin: 0 10px; }
-END_OF_EXPECTED
-            ),
-            array(
-                '#368 - self in selector', <<<'END_OF_SCSS'
-.test {
-    &:last-child:not(+ &:first-child) {
-      padding-left: 10px;
-    }
-}
-END_OF_SCSS
-                , <<<END_OF_EXPECTED
-.test:last-child:not(+ .test:first-child) {
-  padding-left: 10px; }
-END_OF_EXPECTED
-            ),
-            array(
-                '#371 - nested self selector', <<<'END_OF_SCSS'
-ul, ol {
-    & & {
-      display: block;
-    }
-  }
-END_OF_SCSS
-                , <<<END_OF_EXPECTED
-ul ul, ol ul, ul ol, ol ol {
-  display: block; }
-END_OF_EXPECTED
-            ),
 /*************************************************************
             array(
                 '', <<<'END_OF_SCSS'
diff --git a/tests/inputs/at_root.scss b/tests/inputs/at_root.scss
index 86d3f559..7e4dbc0b 100644
--- a/tests/inputs/at_root.scss
+++ b/tests/inputs/at_root.scss
@@ -220,3 +220,15 @@ $table-padding: 10px !default;
     text-decoration: none;
   }
 }
+
+// variable scoping
+$test1: 'foo';
+.any {
+  $test2: 'bar';
+  @at-root {
+    .other {
+      content: "#{$test2}";
+      content: "#{$test1}";
+    }
+  }
+}
diff --git a/tests/inputs/comments.scss b/tests/inputs/comments.scss
index 3e641cc1..31712ac7 100644
--- a/tests/inputs/comments.scss
+++ b/tests/inputs/comments.scss
@@ -45,4 +45,23 @@ a {
 
 // коммент
 
+$color:red;
+$radius:2px;
+
+/* This is a comment with vars references:
+color:#{$color}
+and a fake #{ doing nothing
+radius:#{$radius}
+ */
+
 // end
+
+// comment position in blocks
+.textimage-background-fullheight {
+  .background {
+    /* @noflip */
+    display: block;
+    /* hop */
+    width: 100%;
+  }
+}
diff --git a/tests/inputs/interpolation.scss b/tests/inputs/interpolation.scss
index 45a5133b..a9419dd6 100644
--- a/tests/inputs/interpolation.scss
+++ b/tests/inputs/interpolation.scss
@@ -139,4 +139,15 @@ div {
 }
 .element {
     @include set-border(#{2px}); // compiles to "2px solid #000"
-}
\ No newline at end of file
+}
+
+$foo: "\
+div > p, \
+div > h1 \
+";
+
+#{$foo} {
+  & > strong {
+    color: red;
+  }
+}
diff --git a/tests/inputs/operators.scss b/tests/inputs/operators.scss
index 31e65b17..096aeb37 100644
--- a/tests/inputs/operators.scss
+++ b/tests/inputs/operators.scss
@@ -191,3 +191,37 @@ $gridRowWidth: 20px;
 {
 width: (2.5 / $gridRowWidth * 100px * 1% );
 }
+
+$and: true and false;
+$or: false or true;
+
+$and1: null and true;  // (null)
+$and2: true and null;  // (null)
+$and3: null and false; // (null)
+$and4: false and null; // false
+$and5: one and null;   // (null)
+$and6: null and one;   // (null)
+
+$or1: null or true;    // true
+$or2: true or null;    // true
+$or3: null or false;   // false
+$or4: false or null;   // (null)
+$or5: one or null;     // one
+$or6: null or one;     // one
+
+#bools-test {
+  a: $and;
+  b: $or;
+  c: $and1;
+  d: $and2;
+  e: $and3;
+  f: $and4;
+  g: $and5;
+  h: $and6;
+  n: $or1;
+  o: $or2;
+  p: $or3;
+  q: $or4;
+  r: $or5;
+  s: $or6;
+}
diff --git a/tests/inputs/selector_functions.scss b/tests/inputs/selector_functions.scss
index e97336e2..258aa8f9 100644
--- a/tests/inputs/selector_functions.scss
+++ b/tests/inputs/selector_functions.scss
@@ -12,3 +12,137 @@
 	}
 }
 
+.is-superselector {
+  content: is-superselector(".is-superselector", ".selector"); /* false */
+}
+.is-superselector1 {
+  content: is-superselector("a", "a.disabled"); /*true*/
+}
+.is-superselector2 {
+  content: is-superselector("a", "a:not(:visited)"); /*true*/
+}
+
+.is-superselector3 {
+  content: is-superselector("a", "a[href]"); /*true*/
+}
+
+.is-superselector4 {
+  content: is-superselector("a.disabled", "a"); /*false*/
+}
+
+.is-superselector5 {
+  content: is-superselector("a.disabled", "a.foo.disabled"); /* true*/
+}
+
+.is-superselector6 {
+  content: is-superselector("a.disabled", "a.foo#disabled"); /* false*/
+}
+
+.is-superselector7 {
+  content: is-superselector("a", "sidebar a"); /* true*/
+}
+.is-superselector8 {
+  content: is-superselector("sidebar a", "a"); /* false*/
+}
+.is-superselector9 {
+  content: is-superselector("a", "a"); /* true*/
+}
+
+#{selector-append("a", ".disabled")} {
+	content:'a.disabled';
+}
+
+#{selector-append(".accordion", "__copy")} {
+	content:'.accordion__copy';
+}
+
+#{selector-append(".accordion", "__copy, __image")} {
+	content:'.accordion__copy, .accordion__image';
+}
+
+#{selector-append(".accordion, .slider", "__copy, __image")} {
+	content:'.accordion__copy, .slider__copy, .accordion__image, .slider__image';
+}
+
+#{selector-extend("a.disabled", "a", ".link")} {
+	content: "a.disabled, .link.disabled";
+}
+#{selector-extend("a.disabled", "h1", "h2")} {
+	content: "a.disabled";
+}
+
+#{selector-extend(".guide .info", ".info", ".content nav.sidebar")} {
+	content: ".guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar";
+}
+
+#{selector-nest("ul", "li")} {
+	content: "ul li";
+}
+
+#{selector-nest(".alert, .warning", "p")} {
+	content: ".alert p, .warning p";
+}
+
+#{selector-nest(".alert", "&:hover")} {
+	content: ".alert:hover";
+}
+
+#{selector-nest(".accordion", "&__copy")} {
+	content: ".accordion__copy";
+}
+
+@each $selector in selector-parse(".main aside:hover, .sidebar p") {
+  #{$selector} {
+    @each $part in $selector {
+      content: "#{$part}";
+    }
+  }
+}
+
+#{selector-replace("a.disabled", "a", ".link")} {
+	content: ".link.disabled";
+}
+#{selector-replace("a.disabled", "h1", "h2")} {
+	content: "a.disabled";
+}
+
+#{selector-replace(".guide .info", ".info", ".content nav.sidebar")} {
+	content: ".guide .content nav.sidebar, .content .guide nav.sidebar";
+}
+
+#{simple-selectors("a.disabled")} {
+	/* a, .disabled */
+	@each $part in simple-selectors("a.disabled") {
+		content:"#{$part}";
+	}
+}
+#{simple-selectors("main.blog:after")} {
+	/* main, .blog, :after */
+	@each $part in simple-selectors("main.blog:after") {
+		content:"#{$part}";
+	}
+}
+
+#{selector-unify("a", ".disabled")} {
+	content:"a.disabled";
+}
+
+#{selector-unify("a.disabled", "a.outgoing")} {
+	content: "a.disabled.outgoing";
+}
+
+#{selector-unify("a", "h1")} {
+	content: "null";
+}
+
+#{selector-unify(".warning a", "main a")} {
+	content: ".warning main a, main .warning a";
+}
+
+#{selector-unify("main.warning a", "main a.disabled")} {
+	content: "main.warning a.disabled";
+}
+
+#{selector-unify("main .warning a", "main a")} {
+	content: "main .warning a";
+}
diff --git a/tests/inputs/selectors.scss b/tests/inputs/selectors.scss
index 36ae5a2b..0b9092c2 100644
--- a/tests/inputs/selectors.scss
+++ b/tests/inputs/selectors.scss
@@ -287,3 +287,13 @@ ul, ol {
         display: block;
     }
 }
+
+// unicode
+.👤  {
+  display: inline-block;
+}
+
+.❮ {
+  display:inline;
+  content:'↦';
+}
diff --git a/tests/inputs/values.scss b/tests/inputs/values.scss
index 8279447d..b4111ddb 100644
--- a/tests/inputs/values.scss
+++ b/tests/inputs/values.scss
@@ -6,6 +6,8 @@
     width: 80%;
     color: "hello world";
     height: url("http://google.com");
+    background-image: url(//host/image.png
+);
     dads: url(http://leafo.net);
     padding: 10px 10px 10px 10px, 3px 3px 3px;
     textblock: "This is a \
@@ -15,6 +17,7 @@ multiline block \
     content: "This is a \
 multiline string.";
     border-radius: -1px -1px -1px black;
+    grid-template-columns: [avatar] 2fr [body] 6fr;
 }
 
 #subtraction {
@@ -46,3 +49,11 @@ multiline string.";
     $self2: &;
     content:'#{$self2}';
 }
+
+@font-face {
+    unicode-range: U+26;
+    unicode-range: U+0-7F;
+    unicode-range: U+0025-00FF;
+    unicode-range: U+4??;
+    unicode-range: U+0025-00FF, U+4??;
+}
diff --git a/tests/outputs/at_root.css b/tests/outputs/at_root.css
index c80f3594..6fe091bf 100644
--- a/tests/outputs/at_root.css
+++ b/tests/outputs/at_root.css
@@ -107,3 +107,7 @@ a.badge {
 
 .btn:hover, .btn:focus {
   text-decoration: none; }
+
+.other {
+  content: "bar";
+  content: "foo"; }
diff --git a/tests/outputs/comments.css b/tests/outputs/comments.css
index f6f8d184..c66b30bf 100644
--- a/tests/outputs/comments.css
+++ b/tests/outputs/comments.css
@@ -30,3 +30,13 @@ a {
   /* comment 6 */ }
 /* comment 7 */
 /* коммент */
+/* This is a comment with vars references:
+color:red
+and a fake #{ doing nothing
+radius:2px
+ */
+.textimage-background-fullheight .background {
+  /* @noflip */
+  display: block;
+  /* hop */
+  width: 100%; }
diff --git a/tests/outputs/interpolation.css b/tests/outputs/interpolation.css
index d9fd10e5..1b61ba1f 100644
--- a/tests/outputs/interpolation.css
+++ b/tests/outputs/interpolation.css
@@ -77,3 +77,6 @@ a.badge {
 
 .element {
   border: 2px solid #000; }
+
+div > p > strong, div > h1 > strong {
+  color: red; }
diff --git a/tests/outputs/operators.css b/tests/outputs/operators.css
index 50aaa8c0..1ec77ea0 100644
--- a/tests/outputs/operators.css
+++ b/tests/outputs/operators.css
@@ -173,3 +173,13 @@ div {
 
 .foo {
   width: 12.5%; }
+
+#bools-test {
+  a: false;
+  b: true;
+  f: false;
+  n: true;
+  o: true;
+  p: false;
+  r: one;
+  s: one; }
diff --git a/tests/outputs/selector_functions.css b/tests/outputs/selector_functions.css
index d608dc9d..b071ef6b 100644
--- a/tests/outputs/selector_functions.css
+++ b/tests/outputs/selector_functions.css
@@ -7,3 +7,120 @@
 .main aside:hover, .sidebar p {
   content: ".main aside:hover";
   content: ".sidebar p"; }
+
+.is-superselector {
+  content: false;
+  /* false */ }
+
+.is-superselector1 {
+  content: true;
+  /*true*/ }
+
+.is-superselector2 {
+  content: true;
+  /*true*/ }
+
+.is-superselector3 {
+  content: true;
+  /*true*/ }
+
+.is-superselector4 {
+  content: false;
+  /*false*/ }
+
+.is-superselector5 {
+  content: true;
+  /* true*/ }
+
+.is-superselector6 {
+  content: false;
+  /* false*/ }
+
+.is-superselector7 {
+  content: true;
+  /* true*/ }
+
+.is-superselector8 {
+  content: false;
+  /* false*/ }
+
+.is-superselector9 {
+  content: true;
+  /* true*/ }
+
+a.disabled {
+  content: 'a.disabled'; }
+
+.accordion__copy {
+  content: '.accordion__copy'; }
+
+.accordion__copy, .accordion__image {
+  content: '.accordion__copy, .accordion__image'; }
+
+.accordion__copy, .slider__copy, .accordion__image, .slider__image {
+  content: '.accordion__copy, .slider__copy, .accordion__image, .slider__image'; }
+
+a.disabled, .link.disabled {
+  content: "a.disabled, .link.disabled"; }
+
+a.disabled {
+  content: "a.disabled"; }
+
+.guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar {
+  content: ".guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar"; }
+
+ul li {
+  content: "ul li"; }
+
+.alert p, .warning p {
+  content: ".alert p, .warning p"; }
+
+.alert:hover {
+  content: ".alert:hover"; }
+
+.accordion__copy {
+  content: ".accordion__copy"; }
+  .main aside:hover {
+    content: ".main";
+    content: "aside:hover"; }
+  .sidebar p {
+    content: ".sidebar";
+    content: "p"; }
+
+.link.disabled {
+  content: ".link.disabled"; }
+
+a.disabled {
+  content: "a.disabled"; }
+
+.guide .content nav.sidebar, .content .guide nav.sidebar {
+  content: ".guide .content nav.sidebar, .content .guide nav.sidebar"; }
+
+a, .disabled {
+  /* a, .disabled */
+  content: "a";
+  content: ".disabled"; }
+
+main, .blog, :after {
+  /* main, .blog, :after */
+  content: "main";
+  content: ".blog";
+  content: ":after"; }
+
+a.disabled {
+  content: "a.disabled"; }
+
+a.disabled.outgoing {
+  content: "a.disabled.outgoing"; }
+
+ {
+  content: "null"; }
+
+.warning main a, main .warning a {
+  content: ".warning main a, main .warning a"; }
+
+main.warning a.disabled {
+  content: "main.warning a.disabled"; }
+
+main .warning a {
+  content: "main .warning a"; }
diff --git a/tests/outputs/selectors.css b/tests/outputs/selectors.css
index 64d55926..66a6ab15 100644
--- a/tests/outputs/selectors.css
+++ b/tests/outputs/selectors.css
@@ -370,3 +370,10 @@ span a, p a, div a {
 
 ul ul, ul ol, ol ul, ol ol {
   display: block; }
+
+.👤 {
+  display: inline-block; }
+
+.❮ {
+  display: inline;
+  content: '↦'; }
diff --git a/tests/outputs/values.css b/tests/outputs/values.css
index d6937374..473ce76b 100644
--- a/tests/outputs/values.css
+++ b/tests/outputs/values.css
@@ -5,15 +5,14 @@
   width: 80%;
   color: "hello world";
   height: url("http://google.com");
+  background-image: url(//host/image.png);
   dads: url(http://leafo.net);
   padding: 10px 10px 10px 10px, 3px 3px 3px;
-  textblock: "This is a \
-multiline block \
-#not { color: #eee;}";
+  textblock: "This is a multiline block #not { color: #eee;}";
   margin: 4, 3, 1;
-  content: "This is a \
-multiline string.";
-  border-radius: -1px -1px -1px black; }
+  content: "This is a multiline string.";
+  border-radius: -1px -1px -1px black;
+  grid-template-columns: [avatar] 2fr [body] 6fr; }
 
 #subtraction {
   lit: 10 -11;
@@ -35,3 +34,10 @@ multiline string.";
 
 #self {
   content: "#self"; }
+
+@font-face {
+  unicode-range: U+26;
+  unicode-range: U+0-7F;
+  unicode-range: U+0025-00FF;
+  unicode-range: U+4??;
+  unicode-range: U+0025-00FF, U+4??; }
diff --git a/tests/outputs_numbered/at_root.css b/tests/outputs_numbered/at_root.css
index d57926ab..84d79764 100644
--- a/tests/outputs_numbered/at_root.css
+++ b/tests/outputs_numbered/at_root.css
@@ -160,3 +160,9 @@ a.badge:hover, a.badge:focus {
 
 .btn:hover, .btn:focus {
   text-decoration: none; }
+/* line 226, inputs/at_root.scss */
+/* line 229, inputs/at_root.scss */
+
+.other {
+  content: "bar";
+  content: "foo"; }
diff --git a/tests/outputs_numbered/comments.css b/tests/outputs_numbered/comments.css
index 3669d1d8..f7256abb 100644
--- a/tests/outputs_numbered/comments.css
+++ b/tests/outputs_numbered/comments.css
@@ -32,3 +32,15 @@ a {
   /* comment 6 */ }
 /* comment 7 */
 /* коммент */
+/* This is a comment with vars references:
+color:red
+and a fake #{ doing nothing
+radius:2px
+ */
+/* line 60, inputs/comments.scss */
+/* line 61, inputs/comments.scss */
+  .textimage-background-fullheight .background {
+    /* @noflip */
+    display: block;
+    /* hop */
+    width: 100%; }
diff --git a/tests/outputs_numbered/interpolation.css b/tests/outputs_numbered/interpolation.css
index da509491..256dde01 100644
--- a/tests/outputs_numbered/interpolation.css
+++ b/tests/outputs_numbered/interpolation.css
@@ -96,3 +96,8 @@ a.badge {
 /* line 140, inputs/interpolation.scss */
 .element {
   border: 2px solid #000; }
+/* line 149, inputs/interpolation.scss */
+/* line 150, inputs/interpolation.scss */
+
+div > p > strong, div > h1 > strong {
+  color: red; }
diff --git a/tests/outputs_numbered/operators.css b/tests/outputs_numbered/operators.css
index ad4d678e..9a956a2c 100644
--- a/tests/outputs_numbered/operators.css
+++ b/tests/outputs_numbered/operators.css
@@ -174,3 +174,13 @@ div {
 /* line 190, inputs/operators.scss */
 .foo {
   width: 12.5%; }
+/* line 212, inputs/operators.scss */
+#bools-test {
+  a: false;
+  b: true;
+  f: false;
+  n: true;
+  o: true;
+  p: false;
+  r: one;
+  s: one; }
diff --git a/tests/outputs_numbered/selector_functions.css b/tests/outputs_numbered/selector_functions.css
index 7bd5f1b4..c036813c 100644
--- a/tests/outputs_numbered/selector_functions.css
+++ b/tests/outputs_numbered/selector_functions.css
@@ -8,3 +8,122 @@
 .main aside:hover, .sidebar p {
   content: ".main aside:hover";
   content: ".sidebar p"; }
+/* line 15, inputs/selector_functions.scss */
+.is-superselector {
+  content: false;
+  /* false */ }
+/* line 18, inputs/selector_functions.scss */
+.is-superselector1 {
+  content: true;
+  /*true*/ }
+/* line 21, inputs/selector_functions.scss */
+.is-superselector2 {
+  content: true;
+  /*true*/ }
+/* line 25, inputs/selector_functions.scss */
+.is-superselector3 {
+  content: true;
+  /*true*/ }
+/* line 29, inputs/selector_functions.scss */
+.is-superselector4 {
+  content: false;
+  /*false*/ }
+/* line 33, inputs/selector_functions.scss */
+.is-superselector5 {
+  content: true;
+  /* true*/ }
+/* line 37, inputs/selector_functions.scss */
+.is-superselector6 {
+  content: false;
+  /* false*/ }
+/* line 41, inputs/selector_functions.scss */
+.is-superselector7 {
+  content: true;
+  /* true*/ }
+/* line 44, inputs/selector_functions.scss */
+.is-superselector8 {
+  content: false;
+  /* false*/ }
+/* line 47, inputs/selector_functions.scss */
+.is-superselector9 {
+  content: true;
+  /* true*/ }
+/* line 51, inputs/selector_functions.scss */
+a.disabled {
+  content: 'a.disabled'; }
+/* line 55, inputs/selector_functions.scss */
+.accordion__copy {
+  content: '.accordion__copy'; }
+/* line 59, inputs/selector_functions.scss */
+.accordion__copy, .accordion__image {
+  content: '.accordion__copy, .accordion__image'; }
+/* line 63, inputs/selector_functions.scss */
+.accordion__copy, .slider__copy, .accordion__image, .slider__image {
+  content: '.accordion__copy, .slider__copy, .accordion__image, .slider__image'; }
+/* line 67, inputs/selector_functions.scss */
+a.disabled, .link.disabled {
+  content: "a.disabled, .link.disabled"; }
+/* line 70, inputs/selector_functions.scss */
+a.disabled {
+  content: "a.disabled"; }
+/* line 74, inputs/selector_functions.scss */
+.guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar {
+  content: ".guide .info, .guide .content nav.sidebar, .content .guide nav.sidebar"; }
+/* line 78, inputs/selector_functions.scss */
+ul li {
+  content: "ul li"; }
+/* line 82, inputs/selector_functions.scss */
+.alert p, .warning p {
+  content: ".alert p, .warning p"; }
+/* line 86, inputs/selector_functions.scss */
+.alert:hover {
+  content: ".alert:hover"; }
+/* line 90, inputs/selector_functions.scss */
+.accordion__copy {
+  content: ".accordion__copy"; }
+/* line 95, inputs/selector_functions.scss */
+.main aside:hover {
+  content: ".main";
+  content: "aside:hover"; }
+/* line 95, inputs/selector_functions.scss */
+.sidebar p {
+  content: ".sidebar";
+  content: "p"; }
+/* line 102, inputs/selector_functions.scss */
+.link.disabled {
+  content: ".link.disabled"; }
+/* line 105, inputs/selector_functions.scss */
+a.disabled {
+  content: "a.disabled"; }
+/* line 109, inputs/selector_functions.scss */
+.guide .content nav.sidebar, .content .guide nav.sidebar {
+  content: ".guide .content nav.sidebar, .content .guide nav.sidebar"; }
+/* line 113, inputs/selector_functions.scss */
+a, .disabled {
+  /* a, .disabled */
+  content: "a";
+  content: ".disabled"; }
+/* line 119, inputs/selector_functions.scss */
+main, .blog, :after {
+  /* main, .blog, :after */
+  content: "main";
+  content: ".blog";
+  content: ":after"; }
+/* line 126, inputs/selector_functions.scss */
+a.disabled {
+  content: "a.disabled"; }
+/* line 130, inputs/selector_functions.scss */
+a.disabled.outgoing {
+  content: "a.disabled.outgoing"; }
+/* line 134, inputs/selector_functions.scss */
+ {
+  content: "null"; }
+/* line 138, inputs/selector_functions.scss */
+.warning main a, main .warning a {
+  content: ".warning main a, main .warning a"; }
+/* line 142, inputs/selector_functions.scss */
+main.warning a.disabled {
+  content: "main.warning a.disabled"; }
+/* line 146, inputs/selector_functions.scss */
+main .warning a {
+  content: "main .warning a"; }
diff --git a/tests/outputs_numbered/selectors.css b/tests/outputs_numbered/selectors.css
index d2572233..7b6a8571 100644
--- a/tests/outputs_numbered/selectors.css
+++ b/tests/outputs_numbered/selectors.css
@@ -407,3 +407,10 @@ span a, p a, div a {
 
 ul ul, ul ol, ol ul, ol ol {
   display: block; }
+/* line 292, inputs/selectors.scss */
+.👤 {
+  display: inline-block; }
+/* line 296, inputs/selectors.scss */
+.❮ {
+  display: inline;
+  content: '↦'; }
diff --git a/tests/outputs_numbered/values.css b/tests/outputs_numbered/values.css
index af231709..e218a64e 100644
--- a/tests/outputs_numbered/values.css
+++ b/tests/outputs_numbered/values.css
@@ -6,16 +6,15 @@
   width: 80%;
   color: "hello world";
   height: url("http://google.com");
+  background-image: url(//host/image.png);
   dads: url(http://leafo.net);
   padding: 10px 10px 10px 10px, 3px 3px 3px;
-  textblock: "This is a \
-multiline block \
-#not { color: #eee;}";
+  textblock: "This is a multiline block #not { color: #eee;}";
   margin: 4, 3, 1;
-  content: "This is a \
-multiline string.";
-  border-radius: -1px -1px -1px black; }
-/* line 20, inputs/values.scss */
+  content: "This is a multiline string.";
+  border-radius: -1px -1px -1px black;
+  grid-template-columns: [avatar] 2fr [body] 6fr; }
+/* line 23, inputs/values.scss */
 #subtraction {
   lit: 10 -11;
   lit: -1;
@@ -25,14 +24,21 @@ multiline string.";
   var: -90;
   var: -90;
   var: -90; }
-/* line 34, inputs/values.scss */
+/* line 37, inputs/values.scss */
 #special {
   a: 12px expression(1 + (3 / Foo.bar("baz" + "bang") + function() {return 12;}) % 12); }
-/* line 38, inputs/values.scss */
+/* line 41, inputs/values.scss */
 #unary {
   b: 0.5em;
   c: -foo(12px);
   d: +foo(12px); }
-/* line 44, inputs/values.scss */
+/* line 47, inputs/values.scss */
 #self {
   content: "#self"; }
+
+@font-face {
+  unicode-range: U+26;
+  unicode-range: U+0-7F;
+  unicode-range: U+0025-00FF;
+  unicode-range: U+4??;
+  unicode-range: U+0025-00FF, U+4??; }
diff --git a/tests/scss_test.rb b/tests/scss_test.rb
index 3d849d8a..41fa8e75 100644
--- a/tests/scss_test.rb
+++ b/tests/scss_test.rb
@@ -1,4 +1,3 @@
-#!/usr/bin/env ruby
 # -*- coding: utf-8 -*-
 require File.dirname(__FILE__) + '/test_helper'
 
@@ -1015,7 +1014,8 @@ def test_function_args
   end
 
   def test_disallowed_function_names
-    assert_warning(<<WARNING) {render(<<SCSS)}
+    Sass::Deprecation.allow_double_warnings do
+      assert_warning(<<WARNING) {render(<<SCSS)}
 DEPRECATION WARNING on line 1 of test_disallowed_function_names_inline.scss:
 Naming a function "calc" is disallowed and will be an error in future versions of Sass.
 This name conflicts with an existing CSS function with special parse rules.
@@ -1023,7 +1023,7 @@ def test_disallowed_function_names
 @function calc() {}
 SCSS
 
-    assert_warning(<<WARNING) {render(<<SCSS)}
+      assert_warning(<<WARNING) {render(<<SCSS)}
 DEPRECATION WARNING on line 1 of test_disallowed_function_names_inline.scss:
 Naming a function "-my-calc" is disallowed and will be an error in future versions of Sass.
 This name conflicts with an existing CSS function with special parse rules.
@@ -1031,7 +1031,7 @@ def test_disallowed_function_names
 @function -my-calc() {}
 SCSS
 
-    assert_warning(<<WARNING) {render(<<SCSS)}
+      assert_warning(<<WARNING) {render(<<SCSS)}
 DEPRECATION WARNING on line 1 of test_disallowed_function_names_inline.scss:
 Naming a function "element" is disallowed and will be an error in future versions of Sass.
 This name conflicts with an existing CSS function with special parse rules.
@@ -1039,7 +1039,7 @@ def test_disallowed_function_names
 @function element() {}
 SCSS
 
-    assert_warning(<<WARNING) {render(<<SCSS)}
+      assert_warning(<<WARNING) {render(<<SCSS)}
 DEPRECATION WARNING on line 1 of test_disallowed_function_names_inline.scss:
 Naming a function "-my-element" is disallowed and will be an error in future versions of Sass.
 This name conflicts with an existing CSS function with special parse rules.
@@ -1047,7 +1047,7 @@ def test_disallowed_function_names
 @function -my-element() {}
 SCSS
 
-    assert_warning(<<WARNING) {render(<<SCSS)}
+      assert_warning(<<WARNING) {render(<<SCSS)}
 DEPRECATION WARNING on line 1 of test_disallowed_function_names_inline.scss:
 Naming a function "expression" is disallowed and will be an error in future versions of Sass.
 This name conflicts with an existing CSS function with special parse rules.
@@ -1055,13 +1055,14 @@ def test_disallowed_function_names
 @function expression() {}
 SCSS
 
-    assert_warning(<<WARNING) {render(<<SCSS)}
+      assert_warning(<<WARNING) {render(<<SCSS)}
 DEPRECATION WARNING on line 1 of test_disallowed_function_names_inline.scss:
 Naming a function "url" is disallowed and will be an error in future versions of Sass.
 This name conflicts with an existing CSS function with special parse rules.
 WARNING
 @function url() {}
 SCSS
+    end
   end
 
   def test_allowed_function_names
@@ -2172,7 +2173,7 @@ def test_selector_interpolation_at_dashes
   end
 
   def test_selector_interpolation_in_reference_combinator
-    assert_equal <<CSS, render(<<SCSS)
+    silence_warnings {assert_equal <<CSS, render(<<SCSS)}
 .foo /a/ .bar /b|c/ .baz {
   a: b; }
 CSS
@@ -2286,16 +2287,16 @@ def test_media_interpolation_with_reparse
 
   def test_moz_document_interpolation
     assert_equal <<CSS, render(<<SCSS)
-@-moz-document url(http://sass-lang.com/),
-               url-prefix(http://sass-lang.com/docs),
+@-moz-document url(https://sass-lang.com/),
+               url-prefix(https://sass-lang.com/docs),
                domain(sass-lang.com),
                domain("sass-lang.com") {
   .foo {
     a: b; } }
 CSS
 $domain: "sass-lang.com";
-@-moz-document url(http://\#{$domain}/),
-               url-prefix(http://\#{$domain}/docs),
+@-moz-document url(https://\#{$domain}/),
+               url-prefix(https://\#{$domain}/docs),
                domain(\#{$domain}),
                \#{domain($domain)} {
   .foo {a: b}
@@ -2340,7 +2341,7 @@ def test_supports_bubbling
 
   def test_random_directive_interpolation
     assert_equal <<CSS, render(<<SCSS)
-@foo url(http://sass-lang.com/),
+@foo url(https://sass-lang.com/),
      domain("sass-lang.com"),
      "foobarbaz",
      foobarbaz {
@@ -2348,7 +2349,7 @@ def test_random_directive_interpolation
     a: b; } }
 CSS
 $domain: "sass-lang.com";
-@foo url(http://\#{$domain}/),
+@foo url(https://\#{$domain}/),
      \#{domain($domain)},
      "foo\#{'ba' + 'r'}baz",
      foo\#{'ba' + 'r'}baz {
@@ -3387,22 +3388,22 @@ def test_rules_beneath_properties
   def test_uses_property_exception_with_star_hack
     render <<SCSS
 foo {
-  *bar:baz [fail]; }
+  *bar:baz <fail>; }
 SCSS
     assert(false, "Expected syntax error")
   rescue Sass::SyntaxError => e
-    assert_equal 'Invalid CSS after "  *bar:baz ": expected ";", was "[fail]; }"', e.message
+    assert_equal 'Invalid CSS after "  *bar:baz <fail>": expected expression (e.g. 1px, bold), was "; }"', e.message
     assert_equal 2, e.sass_line
   end
 
   def test_uses_property_exception_with_colon_hack
     render <<SCSS
 foo {
-  :bar:baz [fail]; }
+  :bar:baz <fail>; }
 SCSS
     assert(false, "Expected syntax error")
   rescue Sass::SyntaxError => e
-    assert_equal 'Invalid CSS after "  :bar:baz ": expected ";", was "[fail]; }"', e.message
+    assert_equal 'Invalid CSS after "  :bar:baz <fail>": expected expression (e.g. 1px, bold), was "; }"', e.message
     assert_equal 2, e.sass_line
   end
 
@@ -3420,22 +3421,22 @@ def test_uses_rule_exception_with_dot_hack
   def test_uses_property_exception_with_space_after_name
     render <<SCSS
 foo {
-  bar: baz [fail]; }
+  bar: baz <fail>; }
 SCSS
     assert(false, "Expected syntax error")
   rescue Sass::SyntaxError => e
-    assert_equal 'Invalid CSS after "  bar: baz ": expected ";", was "[fail]; }"', e.message
+    assert_equal 'Invalid CSS after "  bar: baz <fail>": expected expression (e.g. 1px, bold), was "; }"', e.message
     assert_equal 2, e.sass_line
   end
 
   def test_uses_property_exception_with_non_identifier_after_name
     render <<SCSS
 foo {
-  bar:1px [fail]; }
+  bar:1px <fail>; }
 SCSS
     assert(false, "Expected syntax error")
   rescue Sass::SyntaxError => e
-    assert_equal 'Invalid CSS after "  bar:1px ": expected ";", was "[fail]; }"', e.message
+    assert_equal 'Invalid CSS after "  bar:1px <fail>": expected expression (e.g. 1px, bold), was "; }"', e.message
     assert_equal 2, e.sass_line
   end
 
@@ -3649,6 +3650,40 @@ def test_raw_newline_warning
 
   # Regression
 
+  # Regression test for #2031.
+  def test_no_interpolation_warning_in_nested_selector
+    assert_no_warning {assert_equal(<<CSS, render(<<SCSS))}
+z a:b(n+1) {
+  x: y; }
+CSS
+z {
+  a:b(n+\#{1}) {
+    x: y;
+  }
+}
+SCSS
+  end
+
+  # Ensures that the fix for #2031 doesn't hide legitimate warnings.
+  def test_interpolation_warning_in_selector_like_property
+    assert_warning(<<WARNING) {assert_equal(<<CSS, render(<<SCSS))}
+DEPRECATION WARNING on line 2 of #{filename_for_test :scss}:
+\#{} interpolation near operators will be simplified in a future version of Sass.
+To preserve the current behavior, use quotes:
+
+  unquote("n+1")
+
+You can use the sass-convert command to automatically fix most cases.
+WARNING
+z {
+  a: b(n+1); }
+CSS
+z {
+  a:b(n+\#{1});
+}
+SCSS
+  end
+
   def test_escape_in_selector
     assert_equal(<<CSS, render(".\\!foo {a: b}"))
 .\\!foo {
@@ -3791,7 +3826,7 @@ def test_loud_comment_in_compressed_mode
   def test_parsing_decimals_followed_by_comments_doesnt_take_forever
     assert_equal(<<CSS, render(<<SCSS))
 .foo {
-  padding: 4.21053% 4.21053% 5.63158%; }
+  padding: 4.2105263158% 4.2105263158% 5.6315789474%; }
 CSS
 .foo {
   padding: 4.21052631578947% 4.21052631578947% 5.631578947368421% /**/
@@ -3824,7 +3859,19 @@ def test_import_comments_in_imports
   end
 
   def test_reference_combinator_with_parent_ref
-    assert_equal <<CSS, render(<<SCSS)
+    silence_warnings {assert_equal <<CSS, render(<<SCSS)}
+a /foo/ b {
+  c: d; }
+CSS
+a {& /foo/ b {c: d}}
+SCSS
+  end
+
+  def test_reference_combinator_warning
+    assert_warning(<<WARNING) {assert_equal <<CSS, render(<<SCSS)}
+DEPRECATION WARNING on line 1, column 8 of test_reference_combinator_warning_inline.scss:
+The reference combinator /foo/ is deprecated and will be removed in a future release.
+WARNING
 a /foo/ b {
   c: d; }
 CSS
@@ -3894,12 +3941,13 @@ def test_interpolation_with_bracket_on_next_line
 SCSS
   end
 
-  def test_extra_comma_in_mixin_arglist_error
-    assert_raise_message(Sass::SyntaxError, <<MESSAGE.rstrip) {render <<SCSS}
-Invalid CSS after "...clude foo(bar, ": expected mixin argument, was ");"
-MESSAGE
-@mixin foo($a1, $a2) {
-  baz: $a1 $a2;
+  def test_extra_comma_in_mixin_arglist
+    assert_equal <<CSS, render(<<SCSS)
+.bar {
+  baz: bar; }
+CSS
+@mixin foo($a1,) {
+  baz: $a1;
 }
 
 .bar {
@@ -3908,6 +3956,39 @@ def test_extra_comma_in_mixin_arglist_error
 SCSS
   end
 
+
+  def test_extra_comma_between_parameters_in_mixin_arglist
+    assert_raise_message(Sass::SyntaxError, "Invalid CSS after \"...nclude foo(bar,\": expected \")\", was \", baz );\"") {render <<SCSS}
+@mixin foo($a1, $a2) {
+  baz: $a1;
+  bef: $a2;
+}
+
+.bar {
+  @include foo(bar,, baz );
+}
+SCSS
+  end
+
+
+  def test_extra_comma_in_mixin_arglist_ending_needs_have_parentheses_after
+    assert_raise_message(Sass::SyntaxError, "Invalid CSS after \"    bri,\": expected \")\", was \"};\"") {render <<SCSS}
+@mixin foo($a1, $a2) {
+  baz: $a1;
+  bal: $a2;
+}
+
+.bar {
+  @include foo(
+    bar,
+    bri,
+  };
+}
+SCSS
+  end
+
+
+
   def test_interpolation
     assert_equal <<CSS, render(<<SCSS)
 ul li#foo a span.label {
@@ -4144,4 +4225,14 @@ def test_import_with_supports_clause
 SASS
   end
 
+  def test_crlf
+    # Attempt to reproduce https://github.com/sass/sass/issues/1985
+    assert_equal(<<CSS, render(<<SCSS))
+p {
+  margin: 0; }
+CSS
+p {\r\n   margin: 0;\r\n}
+SCSS
+  end
+
 end