Responsive YouTube videos

assets/sass/_base.sass

@@ -9,3 +9,16 @@ main
 
     img
         @extend .img-responsive
+
+.embed-container
+    padding: 56.25% 0 0
+    position: relative
+    width: 100%
+
+    iframe,
+    embed
+        height: 100%
+        left: 0
+        position: absolute
+        top: 0
+        width: 100%

src/AppBundle/Twig/YouTubeExtension.php

@@ -30,7 +30,9 @@ class YouTubeExtension extends Twig_Extension
     public function embedCode($videoId)
     {
         return sprintf(
-            '<iframe width="560" height="315" src="https://www.youtube.com/embed/%s" frameborder="0" allowfullscreen></iframe>',
+            '<div class="embed-container">
+            <iframe src="https://www.youtube.com/embed/%s" frameborder="0" allowfullscreen></iframe>
+            </div>',
             $videoId
         );
     }