JSFiddle - React, Tailwind, and code Playground

by Jeff

HTML

<div class="sidebar">
<div class="inner">
test
</div>
</div>

CSS

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width:30%;
  background: #f00;
}

.inner {
  overflow-y:auto;
  width: 100%;
}