How to Use the CSS Z-index Property

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In Brief...

The z-index property specifies the stack level of an element on the page compared to other elements in its same flow. Learn how to use the z-index property in the following steps.

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Instructions

  1. Set the z-index property for a selector.

    The z-index property takes a number as a value. The higher an element's z-index value, the closer to the user it appears.

  2. 
    .logo {
    	position:absolute;
    	top: 70px;
    	left: 50px;
    	z-index: 20;
    }
    	
  3. To see how the z-index property works, position another element so that it overlaps the first element and give it a different z-index value.
  4. 
    .logo {
    	position:absolute;
    	top: 70px;
    	left: 50px;
    	z-index: 20;
    }
    .logo2 {
    	position:absolute;
    	top: 75px;
    	left: 55px;
    	z-index: 10;
    }
    	
  5. The following example demonstrates the z-index property:
    <!DOCTYPE HTML>
    <html>
    <head>
    <meta charset="UTF-8">
    <style type="text/css">
    .logo {
    	position:absolute;
    	font-family:Century;
    	font-size:2em;
    	font-weight:bold;
    	z-index:20;
    }
    #logo1 {
    	left:50px;
    	top:50px;
    	color:#00f;
    }
    #logo2 {
    	left:52px;
    	top:52px;
    	color:#f00;
    	z-index:10;
    }
    .box {
    	position:absolute;
    	height:100px;
    	width:100px;
    	border:15px solid #000;
    }
    #box1 {
    	left:150px;
    	top:150px;
    	border-color:#f00;
    	z-index:40;
    }
    #box2 {
    	left:185px;
    	top:185px;
    	border-color:#00f;
    	z-index:30;
    }
    #box3 {
    	left:185px;
    	top:150px;
    	border-color:#060;
    	z-index:20;
    }
    #box4 {
    	left:150px;
    	top:185px;
    	border-color:#f60;
    	z-index:10;
    }
    </style>
    <title>CSS Z-Index</title>
    </head>
    <body>
    	<h1>CSS Z-Index</h1>
    	<div id="logo1" class="logo">Webucator</div>
    	<div id="logo2" class="logo">Webucator</div>
    	<div id="box1" class="box"></div>
    	<div id="box2" class="box"></div>
    	<div id="box3" class="box"></div>
    	<div id="box4" class="box"></div>
    </body>
    </html>
    This code renders the following:
    z-index demo

Author: Chris Minnick

Chris is a prolific author and trainer, and the CEO of WatzThis?. His published books include Writing Computer Code, JavaScript for Kids, Coding with JavaScript For Dummies, Beginning HTML5 and CSS3 For Dummies, Webkit For Dummies, CIW eCommerce Certification Bible, and New Riders' XHTML.

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