<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"> <html> <head> <style> div { width: 100px; height: 100px; } .green { background-color: green; } .red { background-color: red; } .overflow { overflow: hidden; } .positioned { position: absolute; } .fixed { position: fixed; left: 100px; top: 100px; } .offset { margin-left: 100px; margin-top: 100px; } </style> <body> You should see a 100x100 green square below. If you see nothing at all or see any red, the test has failed. This test is checking to make sure overflow is done using a containing block model, and that a fixed positioned element inside an absolute positioned element is not considered overflow. <div class="overflow positioned"> <div class="fixed"> <div class="offset green overflow"></div> </div> </div>