<div id="div1">
	  <h1>div #1</h1>
	  position: relative;
	  z-index: 5;
	</div>

	<div id="div3">
	  <div id="div4">
		<h1>div #4</h1>
		position: relative;
		z-index: 6;
	  </div>

	  <h1>div #3</h1>
	  position: absolute;
	  z-index: 4;
	</div>