Embeds
Create responsive video or slideshow embeds based on the width of the parent by creating an intrinsic ratio that scales on any device.
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;
    © 2011–2020 Twitter, Inc.
© 2011–2020 The Bootstrap Authors
Code licensed under the MIT License.
Documentation licensed under the Creative Commons Attribution License v3.0.
    https://getbootstrap.com/docs/4.5/utilities/embed/