<!DOCTYPE HTML> <html reftest-async-scroll> <body> <div style="width:400px; height:500px; overflow:hidden; border:2px solid black" reftest-displayport-x="0" reftest-displayport-y="0" reftest-displayport-w="800" reftest-displayport-h="2000" reftest-async-scroll-x="0" reftest-async-scroll-y="50"> <div style="height:500px"></div> <div style="height:100px; width:200px; float:left; background:purple"></div> <div style="opacity:0.5"> <div style="left:200px; top:0; height:800px; width:300px; float:left; background:yellow; position:absolute; z-index:1;"></div> <div style="height:100px; width:200px; float:left; background:purple; position:relative; z-index:2;"></div> </div> </div>