JSFiddle - React, Tailwind, and code Playground

HTML

<div id="647271"></div>
<div class="647271"></div>
<div class="ok"></div>

CSS

#647271,
.647271 {
  width: 100px;
  height: 100px;
  background: red;
}

.ok {
  width: 100px;
  height: 100px;
  background: green;
}