header{margin:20px;padding:20px;position:absolute;left:;background-color:grey;width:300px;height:auto;border:1px solid black}.button{background-color:white;color:black;border:1px solid black;border-radius:4px}.button:hover{background-color:black;color:white;border:1px solid white;border-radius:4px}section{position:absolute;background-color:grey;width:300px;height:auto;border:1px solid black;padding:20px;margin:20px;top:300px}