<!DOCTYPE html> <meta charset="utf-8"> <title>CSS Transitions Test: transition-property - z-index</title> <link rel="author" title="Intel" href="http://www.intel.com"> <link rel="author" title="Shiyou Tan" href="mailto:shiyoux.tan@intel.com"> <link rel="help" href="https://drafts.csswg.org/web-animations-1/#animation-type"> <link rel="help" href="https://www.w3.org/TR/CSS22/visuren.html#z-index"> <meta name="flags" content="ahem"> <meta name="assert" content="Test checks that the 'z-index' property is animatable."> <style> div { height: 100px; width: 100px; } #ref { background-color: red; z-index: 1; } #test { background-color: green; position: relative; top: -100px; transition-duration: 2s; transition-property: z-index; transition-timing-function: linear; z-index: -100; } </style> <body> <p>Click red square below. Test passes if the color of square changes to green after waiting a moment.</p> <div id="ref"></div> <div id="test"></div> <script> (function() { var test = document.querySelector("#test"); document.addEventListener("click", function(evt) { test.setAttribute("style", "z-index: 100;"); }, false); })(); </script> </body>