Scaling, Set-Proportion iframes
This simple technique works by creating an element with a proportion that matches the video and then sizing and positioning the video
<iframe> to fill that space.
Start with a container around the video
(Always include a
title attribute for accessibility.)
Top or bottom
padding sets the proportion - for example 56.25% for the common 16:9 aspect ratio - and the
<iframe> is positioned and sized to fill the container.
The above CSS works for videos that span the full width of their parent element. For fixed or relative width videos - like
width:50% in a two-column layout - set the padding on a pseudo element, rather than directly on the container.
This example also uses a technique to load embedded YouTube videos on demand to reduce initial-load page weight and improve loading speed: