<!doctype html> <html lang=en> <meta charset=utf-8> <title>CSS-contain test: paint containment use the padding edge</title> <link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net"> <style> div { width: 100px; height: 100px; background: blue; padding: 50px; border-radius: 100px; overflow: hidden } div::before { content:""; display: block; background: green; width: 100px; height: 100px; } </style> <p>Test passes if there is a green square in a rounded blue box, and no red. <div></div>