About
Rules are directly applied to <iframe>, <embed>, <video>, and <object> elements; optionally use an explicit descendant class .embed-responsive-item when you want to match the styling for other attributes.
Pro-Tip! You don’t need to include frameborder="0" in your <iframe>s as we override that for you.
Example
Wrap any embed like an <iframe> in a parent element with .embed-responsive and an aspect ratio. The .embed-responsive-item isn’t strictly required, but we encourage it.
<div class="embed-responsive embed-responsive-16by9">
<iframe class="embed-responsive-item" src="https://www.youtube.com/embed/zpOULjyy-n8?rel=0" allowfullscreen></iframe>
</div>Aspect ratios
Aspect ratios can be customized with modifier classes. By default the following ratio classes are provided:
<!-- 21:9 aspect ratio -->
<div class="embed-responsive embed-responsive-21by9">
<iframe class="embed-responsive-item" src="..."></iframe>
</div>
<!-- 16:9 aspect ratio -->
<div class="embed-responsive embed-responsive-16by9">
<iframe class="embed-responsive-item" src="..."></iframe>
</div>
<!-- 4:3 aspect ratio -->
<div class="embed-responsive embed-responsive-4by3">
<iframe class="embed-responsive-item" src="..."></iframe>
</div>
<!-- 1:1 aspect ratio -->
<div class="embed-responsive embed-responsive-1by1">
<iframe class="embed-responsive-item" src="..."></iframe>
</div>Within _variables.scss, you can change the aspect ratios you want to use. Here’s an example of the $embed-responsive-aspect-ratios list:
$embed-responsive-aspect-ratios: (
(21 9),
(16 9),
(4 3),
(1 1)
) !default;