JSFiddle - React, Tailwind, and code Playground

by joplomacedo

HTML

<div style="width:1300px">
  <ul class="ul-length">
    <li> A </li>
    <li> B </li>
    <li class="fillgap"/>
  </ul>
</div>

CSS

.ul-length {
  position: relative;
  with:100%;
}

.fillgap {
  position:absolute;
  width:100%; 
  left: 0;
    
  /*show me*/
  height: 1px;
  background: black;
}