<body style="margin:0px"> <div style="width: 100px; height: 100px; position: absolute; left: 100px; top: 100px; background-color: red">FAIL</div> <div id="outer" style="opacity: 0.5; margin: 100px"> <div style="position: relative; background-color: green; width: 100px; height: 100px">PASS</div> </div> You should see a 100x100 green rect at 100x100 above with the word PASS. There should be no red on this page. This is a test case for https://bugs.webkit.org/show_bug.cgi?id=25252 <script> function doTest() { document.getElementById("outer").style.opacity = 1.0; if (window.testRunner) testRunner.notifyDone(); } if (window.testRunner) testRunner.waitUntilDone(); // Delay until after the first paint setTimeout(doTest, 0); </script> </body>