:root{--primary-green: #22c55e;--yellow-tile: #ffd54f;--red-tile: #ff7979;--light-gray: #f0f0f0;--dark-text: #333}*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,sans-serif;line-height:1.6;color:var(--dark-text)}h1,h2,h3{margin:0 0 1rem}button{font-family:inherit}a{color:var(--primary-green)}