diff --git a/package.json b/package.json
index 3d3bceee..874be5af 100644
--- a/package.json
+++ b/package.json
@@ -25,7 +25,7 @@
   "dependencies": {
     "cheerio": "1.0.0-rc.2",
     "css-tree": "1.0.0-alpha.28",
-    "csso": "~3.5.0",
+    "csso": "ianvonholt/csso",
     "filesize": "^3.5.11",
     "minimist": "^1.2.0",
     "puppeteer": "^1.4.0"
diff --git a/src/run.js b/src/run.js
index 3e154145..44f7a8d7 100644
--- a/src/run.js
+++ b/src/run.js
@@ -1,10 +1,12 @@
 'use strict';
 
+// @ts-ignore
 const puppeteer = require('puppeteer');
 // @ts-ignore
 const csso = require('csso');
 // @ts-ignore
 const csstree = require('css-tree');
+// @ts-ignore
 const cheerio = require('cheerio');
 const utils = require('./utils');
 const { createTracker } = require('./tracker');
@@ -12,6 +14,8 @@ const url = require('url');
 
 const isOk = response => response.ok() || response.status() === 304;
 
+const skippableResourceTypes = ['font', 'media', 'ping', 'xhr'];
+
 /**
  * Take in a csstree AST, mutate it and return a csstree AST.
  * The mutation is about:
@@ -126,7 +130,7 @@ const processPage = ({
     let fulfilledPromise = false;
 
     const tracker = createTracker(page);
-    const safeReject = error => {
+    const safeReject = (error, fatal) => {
       if (!fulfilledPromise) {
         if (error.message.startsWith('Navigation Timeout Exceeded')) {
           const urls = tracker.urls();
@@ -138,8 +142,12 @@ const processPage = ({
             error.message += `\nFor ${urls[0]}`;
           }
         }
-        tracker.dispose();
-        reject(error);
+        if (fatal) {
+          tracker.dispose();
+          reject(error);
+        } else {
+          console.warn(error);
+        }
       }
     };
 
@@ -181,7 +189,7 @@ const processPage = ({
           request.abort();
         } else if (!loadimages && resourceType === 'image') {
           request.abort();
-        } else if (resourceType === 'font') {
+        } else if (skippableResourceTypes.includes(resourceType)) {
           request.abort();
         } else if (stylesheetAsts[requestUrl]) {
           // no point downloading this again
@@ -203,6 +211,12 @@ const processPage = ({
       page.on('response', response => {
         const responseUrl = response.url();
         const resourceType = response.request().resourceType();
+        
+        // Log third-party content for possible future blacklisting
+        if (!responseUrl.startsWith(pageUrl)) {
+          console.log(resourceType, responseUrl);
+        }
+
         if (response.status() >= 400) {
           return safeReject(
             new Error(`${response.status()} on ${responseUrl}`)
@@ -218,6 +232,10 @@ const processPage = ({
           redirectResponses[responseUrl] = redirectsTo;
         } else if (resourceType === 'stylesheet') {
           response.text().then(text => {
+            // Double semicolons can crash csso.
+            while (/;\s*;/.test(text)) {
+              text = text.replace(/;\s*;/g, ';');
+            }
             const ast = csstree.parse(text);
             csstree.walk(ast, node => {
               if (node.type === 'Url') {
@@ -264,7 +282,10 @@ const processPage = ({
         await page.setJavaScriptEnabled(false);
         response = await page.goto(pageUrl);
         if (!isOk(response)) {
-          return safeReject(new Error(`${response.status()} on ${pageUrl}`));
+          return safeReject(
+            new Error(`${response.status()} on ${pageUrl}`),
+            true // fatal
+          );
         }
         const htmlVanilla = await page.content();
         doms.push(cheerio.load(htmlVanilla));
@@ -288,7 +309,8 @@ const processPage = ({
       response = await page.goto(pageUrl, { waitUntil: 'networkidle0' });
       if (!isOk(response)) {
         return safeReject(
-          new Error(`${response.status()} on ${pageUrl} (second time)`)
+          new Error(`${response.status()} on ${pageUrl} (second time)`),
+          true // fatal
         );
       }
       const evalWithJavascript = await page.evaluate(() => {
@@ -306,7 +328,10 @@ const processPage = ({
             link.media !== 'print' &&
             !link.href.toLowerCase().startsWith('data:')
           ) {
-            hrefs.push(link.href);
+            // Fragments are omitted from request.url() and response.url(),
+            // so we also need to strip them here, otherwise the hrefs
+            // won't always match when we check for missing ASTs.
+            hrefs.push(link.href.replace(/#.*$/, ''));
           }
         });
         return {
@@ -333,7 +358,7 @@ const processPage = ({
         resolve();
       }
     } catch (e) {
-      return safeReject(e);
+      return safeReject(e, true); // fatal
     }
   });
 
@@ -405,8 +430,8 @@ const minimalcss = async options => {
     );
   });
   if (missingASTs.length) {
-    throw new Error(
-      `Found stylesheets that failed to download (${missingASTs})`
+    console.warn(
+      `Found stylesheets that failed to download: (${missingASTs})`
     );
   }
 
@@ -445,6 +470,9 @@ const minimalcss = async options => {
     }
     const ast = stylesheetAsts[href];
 
+    // Missing stylesheet would crash csstree.
+    if (!ast) return;
+
     csstree.walk(ast, {
       visit: 'Rule',
       enter: function(node, item, list) {
@@ -456,6 +484,12 @@ const minimalcss = async options => {
           return;
         }
 
+        if (!node.prelude.children) {
+          // delete malformed rule
+          list.remove(item);
+          return;
+        }
+
         node.prelude.children.forEach((node, item, list) => {
           // Translate selector's AST to a string and filter pseudos from it
           // This changes things like `a.button:active` to `a.button`