JSFiddle - React, Tailwind, and code Playground

HTML

<div class="rect">Hover me</div>

CSS

.rect{
  background-color:LightSeaGreen ;
  width:100px;
  height:100px;
  transition-property: background-color;
  transition-duration: 1s;
  text-align:center;
  display:flex;
  align-items: center;
  justify-content: center;
}

.rect:hover{
  background-color:Tomato ;
}