JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">
  <div class="div1">DIV 1</div>
  <div class="div2">DIV 2</div>
  <div class="div3">DIV 3</div>
</div>

CSS

* { box-sizing: border-box; margin: 0; padding: 0; }
.box {
  border: 1px solid black;
  display: flex;
}
.box > div {
  border: 1px solid red;
  width: 33%;
  height: 150px;
}

@media screen and (max-width: 400px)  {
  .box {
    flex-direction: column-reverse;
  }
  .box > div {
    width: 100%;
  }
}