JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block-item"></div>
<div class="block-item"></div>
<div class="block-item"></div>
<div class="block-item"></div>
<div class="block-item"></div>

SCSS

.block-item {
  float: left;
  position: relative;
  cursor: pointer;
  width: 30px;
  height: 30px;
  margin: 5px;
  background-color: blue;
  
  &.active, &:hover {
    background-color: green;
  }
}