JSFiddle - React, Tailwind, and code Playground

HTML

<div class="black">
    <div class="yellow">
    </div>
    <div class="purple">
    </div>
</div>

CSS

.black{padding-left:30px;height:100px;position:relative;}
.yellow{background:yellow;width:100%;height:100%;}
.purple{background:purple;width:30px;height:100%;position:absolute;left:0;top:0;}