update2

pfosten/vendor/tijsverkoyen/css-to-inline-styles/composer.json

@@ -12,11 +12,11 @@
     }
   ],
   "require": {
-    "php": "^5.5 || ^7",
-    "symfony/css-selector": "^2.7|~3.0"
+    "php": "^5.5 || ^7.0",
+    "symfony/css-selector": "^2.7 || ^3.0 || ^4.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "~4.8|5.1.*"
+    "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.0"
   },
   "autoload": {
     "psr-4": {
@@ -25,7 +25,7 @@
   },
   "extra": {
     "branch-alias": {
-      "dev-master": "2.0.x-dev"
+      "dev-master": "2.2.x-dev"
     }
   }
 }

pfosten/vendor/tijsverkoyen/css-to-inline-styles/src/Css/Processor.php

@@ -33,7 +33,8 @@ class Processor
     {
         $css = '';
         $matches = array();
-        preg_match_all('|<style(?:\s.*)?>(.*)</style>|isU', $html, $matches);
+        $htmlNoComments = preg_replace('|<!--.*?-->|s', '', $html);
+        preg_match_all('|<style(?:\s.*)?>(.*)</style>|isU', $htmlNoComments, $matches);
 
         if (!empty($matches[1])) {
             foreach ($matches[1] as $match) {