JSFiddle - React, Tailwind, and code Playground

HTML

<header>
  <div>
  <div class="box"></div>
  <div class="box2"></div>
  <div class="box3"></div>

CSS

.box{
  width: 200px;
  height: 200px;
  background-color: red;
}
.box2{
  width: 250px;
  height: 250px;
  background-color: blue;
}
.box3{
  width: 150px;
  height: 150px;
  background-color: pink;
}
@media screen and (max-width:480px){
  .box{
    width: 200px;
    height: 200px;
    background-color: black;
  }
  .box2{
    width: 250px;
    height: 250px;
    background-color: green;
  }
  .box3{
    width: 150px;
    height: 150px;
    background-color: grey;
  }
}