<!DOCTYPE html> <html> <head> <style> #container { will-change: transform; position: absolute; left: 200px; top: 100px; width: 100px; height: 100px; background-color: blue; } .fixed { position: fixed; left: 50px; top: 50px; width: 75px; height: 75px; background-color: green } </style> <script src="../../fast/repaint/resources/text-based-repaint.js"></script> <script> function repaintTest() { // Removing "will-change: transform" to the container div should make this // div no longer be the containing block for its fixed position descendant. console.log('debug'); document.getElementById("container").style.willChange = "top"; } onload = runRepaintAndPixelTest; </script> </head> <body> <div id="container"> <div class="fixed"></div> </div> </body> </html>