JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container" class="one-column">
  <div class="col1" style="order:2;">
    ONE
  </div>
  <div class="col2" style="order:1;">
    TWO
  </div>
  <div class="col1" style="order:4;">
    THREE
  </div>  
  <div class="col2" style="order:3;">
    FOUR
  </div>
</div>

CSS

* {
  box-sizing: border-box;
}
div {
  width: 100%;
  height: 100px;
  float: left;
}
#container.one-column {
  display: flex;
  flex-direction: column;
  height: auto;
}
#container {
  display: block;
}
.col1 {
  width: 60%;
  background-color: red;
  height:300px;
  float: left;
}
.col2 {
  width: 40%;
  background-color: blue;
  border: 1px solid white;
  float: right;
}
.one-column > div {
  width: 100%;
}