JSFiddle - React, Tailwind, and code Playground

HTML

<div class="div1">1st</div> 
<div class="div2">2nd</div>

CSS

div.div1, div.div2 {
  position: absolute;
  left: 0;
  right: 0;
  outline: solid 1px #ccc; /* just for making the divs visible */
  margin: 5px; /* just for making the divs visible */
}
div.div1 {
  height: 100px;
  top: 0;
}
div.div2 {
  top: 100px;
  bottom: 0;
}