JSFiddle - React, Tailwind, and code Playground

HTML

<div class="first">div1</div>
<div class="second">div2</div>
<div class="third">div3</div>
<div class="fourth">div4</div>

CSS

.first {
    background-color:red;
    width: 400px;
}
.second {
    background-color:blue;
    width: 200px;
    float:left;
}
.third {
    background-color:green;
    width: 200px;
    float:left;
}
.fourth {
    clear:both;
    background-color:yellow;
    width: 400px;
}