JSFiddle - React, Tailwind, and code Playground

HTML

<div class="root">
  <div class="outer">
    <div class="nav"></div>
  </div>
</div>

CSS

.root {
  background-color: green;
}

.outer {
    display: grid;
    grid-template-rows: 100vh;
    grid-template-columns: 100px;
    padding: 5rem;
    overflow-y: auto;
}

.nav {
  background-color: red;
  height: 150vh;
}

.content {
   background-color: lightblue;
 }
 
* {
  box-sizing: border-box;
}