JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>My Portfolio</title>
    <link rel="stylesheet" type="text/css" href="portfolio.css">
  </head>

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

</html>

CSS

.box{
  position: absolute;
  
  top: 0;
  left: 0; 
  
  width: 18rem;
  height: 500rem;
  
  background-color: #000033;
  z-index: 0;

}

.line{
  position: relative;
  display: block;
  
  top: 6rem;
  left: 0px; 
  
  height: 2px;
  width: 100%;
  
  background-color: #fff;
  z-index: 2;
}