<style>
    	body{background: white; margin:0; padding:0;}
		.header{width: 100%; background: #ccc; position: absolute; left: 0; top: 0; height: 40px; z-index: 10;}

		.sidebar{width:200px; background: yellow; position: absolute; left: 0; top: 0; height: 100%; z-index: 5;}
		.sidebar-content{background: red; margin: 50px 10px 0; }
    </style>