JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="line"></div>
  <div class="box"></div>
</div>

CSS

.parent {
  overflow: auto;
  overflow-x: hidden;
  position: relative;
  height: 300px;
  width: 200px;
  border: 1px solid black;
}

.line {
  border-bottom: 1.5px solid black;
  height: 50px;
  margin-left: 7px;
  margin-right: 7px;
  position: relative;
}

.box {
  position: absolute;
  top: 0;
  height: 100%;
  background-color: red;
  width: 50%;
  left: 20%;
  z-index: 10;
}