<!DOCTYPE html> <html class="reftest-wait"> <title>Test that opacity changes on layers make the Compositor repaint the right area</title> <style> #box { width: 100px; height: 100px; border: 10px solid black; opacity: 1; will-change: opacity; } #box.halfTransparent { opacity: 0.5; } </style> <div id="box"></div> <script> window.addEventListener("MozReftestInvalidate", function (e) { document.getElementById("box").className = "halfTransparent"; document.documentElement.removeAttribute("class"); }); </script>