JSFiddle - React, Tailwind, and code Playground

HTML

<div class="first"></div>
<div class="second"></div>

SCSS

$width-first: 25%;
.first {
  width: $width-first;
  background: red;
  height: 100px;
}
.second {
  margin-left: calc(#{$width-first}/2);
  background: green;
  height: 100px;
}