<!DOCTYPE html> <html class="reftest-wait"> <title>Transform animation whose target is not initially associated with any document creates a stacking context even if it has only 'transform:none' in its keyframe</title> <style> span { height: 100px; width: 100px; position: fixed; background: green; top: 50px; } div { width: 100px; height: 100px; background: blue; } </style> <span></span> <script> var div = document.createElement("div") var anim = div.animate({ transform: ['none', 'none'] }, { duration: 100000 }); document.body.appendChild(div); anim.ready.then(function() { document.documentElement.classList.remove("reftest-wait"); }); </script>