JSFiddle - React, Tailwind, and code Playground

HTML

<style>#1 div.inner{background-color:red}</style>

<div id="1" class="outer">
  content
  <div class="inner">
    more content
  </div>
</div>

<style>#2 div.inner {background-color:green}</style>
<div id="2" class="outer">
  content
  <div class="inner">
    more content
  </div>
</div>

CSS

.outer{
  width:100px;
  height:100px;
  background-color:blue;
}
.inner{
  width:50px;
  height:50px;
  margin:10px;
}