JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div id="main">
        main - 1
        <br>
        main - 2
    </div>    
    <div id="left">
        left
    </div>        
</div>

CSS

.container{
  border: 1px solid black;    
  display: -ms-flexbox;
  display: -webkit-box;
  display: -webkit-flexbox;
  display: -webkit-flex;
  display: flex;  
}

.container > div{
  display: block;      
  width: 100%;
  min-height: 100%;      
}

#left{
  background: pink;
  width: 200px;   
  -webkit-order: 1;
          order: 1;     
}

#main{
  background: lightblue; 
  -webkit-order: 2;
          order: 2;     
}