JSFiddle - React, Tailwind, and code Playground

HTML

<div>
  <h1><span>This</span></h1>
  <h1><span>This</span></h1>
  <h1><span>This</span></h1>

</div>

CSS

h1{ color:#333}
h1 span {
  position: relative;
  font-size: 100px;
  font-weight: 300;
  margin: 0;
  padding:0 0 0 20px;
}

h1 span::before {
  content: "";
  background: red;
  height: .25em;
  position: absolute;
  bottom: .15em;
  z-index: -1;
  width: 100%;
  left: 0;
}