JSFiddle - React, Tailwind, and code Playground

HTML

<figure style="width: 500px"><img src="http://vaughanrockets.typepad.com/.a/6a00d8354d1e6469e2015436bfa67b970c-800wi"></figure>

CSS

img {
    width: 100px;
    height: 100px;
    background: red;
    -webkit-animation: myfirst 5s; /* Chrome, Safari, Opera */
    animation: myfirst 5s;
}

/* Chrome, Safari, Opera */
@-webkit-keyframes myfirst {
    from {width: 100px;}
    to {width: 100%;}
}

/* Standard syntax */
@keyframes myfirst {
    from {width: 100px;}
    to {width: 100%;}
}