*{margin:0;padding:0;box-sizing:border-box}:root{--primary: #2563eb;--bg: #fafafa;--text: #1a1a1a;--text-secondary: #666;--border: #e5e5e5;--radius: 12px}body{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text);line-height:1.6}.container{max-width:640px;margin:0 auto;padding:0 20px}.btn{display:inline-flex;align-items:center;justify-content:center;padding:12px 24px;border-radius:var(--radius);border:none;background:var(--primary);color:#fff;font-size:16px;font-weight:600;cursor:pointer;transition:opacity .2s}.btn:hover{opacity:.9}.card{background:#fff;border:1px solid var(--border);border-radius:var(--radius);padding:20px;margin-bottom:16px}