JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">

</div>
<div class="sidebar">
  <div class="sticky">
  
  </div>
</div>

CSS

.main,.sidebar{
  width:45%;
  height:200vh;
  border:1px black solid;
  float:left;
}
.sticky{
  width:45%;
  height:200px;
  border:1px red solid;
    position: -webkit-sticky;
    position: -moz-sticky;
    position: -ms-sticky;
    position: -o-sticky;
    position: sticky;
    top: 0px;
}