JSFiddle - React, Tailwind, and code Playground

HTML

<div class="thumbar">
    <img class="thumbnails" src="http://www.businessinsider.com/image/4f3433986bb3f7b67a00003c/cute-cat.jpg">
    <img class="thumbnails" src="http://www.businessinsider.com/image/4f3433986bb3f7b67a00003c/cute-cat.jpg">
    <img class="thumbnails" src="http://www.businessinsider.com/image/4f3433986bb3f7b67a00003c/cute-cat.jpg">
    <img class="thumbnails" src="http://www.businessinsider.com/image/4f3433986bb3f7b67a00003c/cute-cat.jpg">
</div>

CSS

body {
    padding: 0px;
    margin: 0px;
}
.thumbar {
}
.thumbnails {
    width: 25%;
    height:auto;
    background: white;
    float: left;
}
@media screen and (max-width : 320px) {
    .thumbnails {
        width: 100%;
        float: none;
    }
}