JSFiddle - React, Tailwind, and code Playground

HTML

<div class='out'>
<ul>
<li>1
<div class='in'><ul>
</li></li>
</ul>
</div>
</li>
<li>2</li>
    <ul>
</div>

CSS

.out{
    width:100%; 
    margin:0 auto; 
    height:150px;
    background:#ccc;
}
.in{
position: absolute;
top:20;
    height:100px;
    width:100%;
    background:#ff0;
}