JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<HTML xml:lang="ru" dir="ltr" xmlns="http://www.w3.org/1999/xhtml" lang="ru">
<HEAD>
	<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
</HEAD>

<BODY >
<div id="top-menu">
    <p>123</p>
</div>

<div class="parent">
   <div class="divL">
      <div class="leftmenu">
         <p>qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq</p>
         <p>wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww</p>
         <p>eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee</p>
      </div>
   </div>
   <div class="box">
      <p>AAAAAAAAAAAAAAAAAAAAAAААААААAAAA</p>
      <p>ББББББББББББББББББББББББББББББББ</p>
      <p>ВВВВВВВВВВВВВВВВВВВВВВВВВВВВВВВВ</p>
   </div>
   <p>1111111111111111111111111111111111</p>
   <p>2222222222222222222222222222222222</p>
   <p>3333333333333333333333333333333333</p>
</div>

</BODY>
</HTML>

CSS

body {
   font-family: Arial, Verdana, Helvetica, sans-serif;
   margin:0;
   padding:0;
   background: #c2c2c2;
}

#top-menu {
   height:30px;
   background:#5977a0;
}

.divL {
	bottom:0;
	top:0;
	left:0;
	position:absolute;
	width: 190px;
	padding: 5px;
	float: left;
	background-color: blue;
	overflow: hidden;
}
.leftmenu {
	overflow: hidden;
	padding: 0px 0px 10px 5px;
   margin: 5px;
	background-color: yellow;
}

.parent {
   margin: 5px;
   position:relative;
}
.box {
	min-width: 900px;
	overflow: hidden;
	margin-left: 205px;
   background-color:red;
}