JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
    <link type="text/css" rel="stylesheet" href="styles.css"/>
</head>
<body>
    <div id="cabecera">
        cabecera
    </div>
    <div id="menu">
        menu
    </div>
    <div id="botones">
        botones
    </div>
    <div id="contenido">
        contenido
    </div>
</body>
</html>

CSS

#cabecera{
    height: 80px;
    background-color: green;
}

#menu{
    float: left;
    height: 80px;
    width: 15%;
    background-color: yellow;
}
 
#botones{
    height: 40px;
    width: 80%;
    float: left;
    background-color: red;
}
#contenido{
    height: 80px;
    width: 80%;
    float: left;
    background-color: blue;
    position:relative;
}
div {margin:10px 10px 0 0}