:root{--primary-color:#2563eb;--background-color:#f8fafc;--text-color:#0f172a}body{margin:0;background:var(--background-color);color:var(--text-color);font-family:system-ui,-apple-system,"Segoe UI",Arial,sans-serif}.container{max-width:1200px;margin:auto;padding:24px}.card{background:#fff;border:1px solid #e5e7eb;border-radius:12px;padding:20px;margin:14px 0}button{cursor:pointer}