<!DOCTYPE html> <html class="reftest-wait"> <style> @keyframes anim { to { transform: rotate(360deg); } } .document-ready div::after { display: none; } div::after { content: ""; } .animation::after { animation: anim 1s infinite; } </style> <div id="target"></div> <script> window.addEventListener('load', () => { target.classList.add('animation'); const psuedo = document.getAnimations()[0].effect.target; target.classList.remove('animation'); psuedo.animate([ { transform: 'rotate(360deg)' } ], 1000); requestAnimationFrame(() => { document.documentElement.classList.add('document-ready'); requestAnimationFrame(() => { document.documentElement.classList.remove('reftest-wait'); }); }); }); </script> </html>