<!DOCTYPE html> <title> Transform animation creates a stacking context even if the transform property is overridden by an !important rule </title> <style> span { height: 100px; width: 100px; position: fixed; background: green; top: 50px; } @keyframes TransformNone { from, to { transform: none; } } #test { width: 100px; height: 100px; background: blue; animation: TransformNone 100s infinite; transform: none !important; } </style> <span></span> <div id="test"></div>