JSFiddle - React, Tailwind, and code Playground

HTML

<div class="header"></div>
<div class="header-right"></div>

CSS

.header{
    float:left;
    background: #efefef;
    background-repeat: no-repeat;
    width: 240px;
    height: 100px;
    }

.header-right{
    overflow:hidden; 
    background-color:#000;
    height: 100px;
    }