JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="header">
        header
    </div>
    <div class="column">
    <div id="left">
       <div class="inner-left">
           left
       </div>
    </div>
    <div id="right">
        <div class="inner-right">
            right
        </div>
    </div>
    </div>
</div>

CSS

body{
padding: 0px;
margin: 0px;
}

#container {
    position: relative;
    width: 100%;
	background-color: yellow;
}

#header {
    position: relative;
    height: 50px;
    padding: 10px;
	background-color: green;
}


#left {
    position: relative;
    height: 200px;
	width: 30%;
	background-color: red;
	float: left;
	display: block;
}
.inner-left {
    padding: 10px 10px;
    color: white;
}
.inner-right {
    padding: 10px 10px;
    color: white;
}
.column {
    width:100%;
}
#right {
    position: relative;
    height: 200px;
	width: 70%;
	float: right;
	background-color: black;
	display: block;
}