JSFiddle - React, Tailwind, and code Playground

by danield770

HTML

<div class="a">
    <img src="http://lorempixel.com/560/315/" width="560" height="315" />
</div>

<div class="a">
    <iframe width="560" height="315" src="http://www.youtube.com/embed/RksyMaJiD8Y" frameborder="0" allowfullscreen></iframe>
</div>

CSS

body { margin:0; }
.a {
    max-width: 560px;
    background: grey;
}
img {
    width: 100%;
    height: auto
}
iframe {
    max-width: 100vw;
    max-height: 56.25vw; /* 315/560 = .5625 */
}