<!-- Any copyright is dedicated to the Public Domain. http://creativecommons.org/publicdomain/zero/1.0/ --> <!DOCTYPE html> <meta charset="utf-8"> <title>Test that overlay scrollbars are on top of positioned siblings when the scrollable frame has a positioned descendant that's higher than the sibling</title> <style> #outer { width: 200px; height: 200px; overflow: auto; } #content { height: 400px; background: cyan; position: relative; z-index: 3; } /* This test has different behavior depending on the type of scrollbar used. * We want the scrollbar to be visible. When overlay scrollbars are used, * they should be visible even when #cover gets between #outer and #content, * but for non-overlay scrollbars, that would cover them so we disable the * cover. */ @media all and (-moz-overlay-scrollbars) { #cover { width: 200px; height: 200px; background: cyan; position: absolute; z-index: 2; } } </style> <div id="cover"></div> <div id="outer"><div id="content"></div></div>