Ratios
Use generated pseudo elements to make an element maintain the aspect ratio of your choosing. Perfect for responsively handling video or slideshow embeds based on the width of the parent.
Ratios on BootstrapExample
<div class="ratio ratio-16x9">
<iframe src="https://www.youtube.com/embed/zpOULjyy-n8?rel=0" allowfullscreen="allowfullscreen" title="YouTube video"></iframe>
</div>
Aspect ratios
1x1
4x3
16x9
21x9
<div class="example-aspect-rarios">
<div class="ratio ratio-1x1">
<div>1x1</div>
</div>
<div class="ratio ratio-4x3">
<div>4x3</div>
</div>
<div class="ratio ratio-16x9">
<div>16x9</div>
</div>
<div class="ratio ratio-21x9">
<div>21x9</div>
</div>
</div>