No support for css functions

[ju1ius]

div.main{
  background-image: linear-gradient(#000, #fff);
}

Stack trace:

PHP Fatal error:  Uncaught exception 'Exception' with message 'Identifier expected, got (#000' in /home/ju1ius/code/php/third-party/PHP-CSS-Parser/CSSParser.php:98
Stack trace:
#0 CSSParser.php(247): CSSParser->parseIdentifier()
#1 CSSParser.php(216): CSSParser->parseValue()
#2 CSSParser.php(204): CSSParser->parseRule()
#3 CSSParser.php(198): CSSParser->parseRuleSet(Object(CSSDeclarationBlock))
#4 CSSParser.php(50): CSSParser->parseSelector()
#5 CSSParser.php(35): CSSParser->parseList(Object(CSSDocument), true)
#6 CSSParser.php(29): CSSParser->parseDocument(Object(CSSDocument))
#7 test.php(84): CSSParser->parse()
#8 {main}
  thrown in CSSParser.php on line 98