JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>index.htm</title>
</head>
<body>

        <div id="header">
            HEADER
        </div><!-- #header -->
        <div id ="parent">
        <div id="nav">
            NAV
        </div><!-- #nav -->
        <div id="content">
            CONTENT
        </div><!-- #content -->
       </div>
</body>
</html>

CSS

#header{
    background-color: Orange;
    height: 65px;
}

#nav{
    background-color: Brown;
    position:absolute;
    width: 235px;
    left:0px;
    top:0px;
    bottom:0px;
}
#content{
    background-color: Purple;
    position:absolute; 
    left:235px;
    top:0px;
    right:0px;
    bottom:0px;
}
#parent{
    margin-top:65px;
    position:absolute; 
    top:0px; 
    left:0px;
    right:0px; 
    bottom:0px;
}