JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li><div class="left">12345</div><div class="right">...</div></li>
    <li><div class="left">123456</div><div class="right">...</div></li>
    <li><div class="left">1234567</div><div class="right">...</div></li>
    <li><div class="left">12345678</div><div class="right">...</div></li>
    <li><div class="left">123456789</div><div class="right">...</div></li>
    <li><div class="left">1234567890</div><div class="right">...</div></li>
</ul>

CSS

ul
{
    list-style:none;
    width:100%;
}
li
{
    clear:both;
    position:relative;
    overflow:hidden;
}
li div
{
    padding:5px;
}
.left
{
    float:left;
    width:20%;
    background-color:blue;
    color:white;
}
.right
{
    
    background-color:gray;
}