<svg width="100" height="100" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"><defs><mask id="a"><path fill="#fff" d="M0 0h100v100H0z"/><circle cx="85" cy="85" r="15"/></mask></defs><path fill="green" mask="url(#a)" d="M0 0h100v100H0z"/></svg>
