JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1"></div>
<div id="div2"></div>

CSS

#div1 {
    height:20px;
    border:1px solid #000;
    /*float:left;*/
}
#div2 {
    float:right;
    width:100px;
    height:100%;
    border:1px solid #F00;
}
html, body { height:100%; }