JSFiddle - React, Tailwind, and code Playground

by Snatch

HTML

<div class="wrapper">
  <div class="box">Box 1</div>
  <div class="box">Box 2</div>
  <div class="box">Box 3</div>
</div>

<div class="button">
My Button
</div>

CSS

html, body {
  height: 100%;
}

.wrapper {
  width:150px;
  height:100%;
  overflow-y:auto;
}

.box {
  width:100px;
  height:150px;
  background:blue;
  border-bottom:2px solid white;
}

.button {
  display:none;
  position:absolute;
  z-index:1;
  top:0;
  right:0;
  width:100px;
  height:100px;
  background: red;
}