JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
  <li>One</li>
  <li>Two</li>
  <li>Three</li>
  <li>Four</li>
  <li>Five</li>
</ul>

CSS

ul {
  list-style-type: none;
  padding: 0;
  width: 100px;
}
li {
  padding: .5em;
  outline: solid 1px gray;
  position: relative;
}

li:hover::after {
  content: '';
  position: absolute;
  left: 95%; right: 0; top: 0; bottom: 0;
  background: orange;
}