JSFiddle - React, Tailwind, and code Playground

HTML

<h1 class="t1">11111111111</h1>
<h1 class="t2">22222222222</h1>
<h1 class="t3">33333333333</h1>

CSS

.t1 {
  font-size: 1em;
  background-color: red;
}
.t2 {
  font-size: 3em;
  background: green;
}
.t3 {
  font-size: 9em;
  background: blue;
}