Make YouTube Embeds Responsive in WordPress [code snippet]

The CSS styles below will make any YouTube video embeds using just the URL responsive. Add this to the bottom of your WordPress theme CSS stylesheet.

.embed-youtube{ position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } 
.embed-youtube iframe, .embed-youtube object, .embed-youtube embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }