.app{max-width:720px;margin:0 auto;padding:48px 24px}.app-header h1{font-size:2rem;margin:0 0 4px}.app-sub{color:#667085;margin:0 0 32px}.app-main{display:grid;gap:16px}.card{border:1px solid #e4e7ec;border-radius:10px;padding:20px 24px;background:#fff}.card h2{font-size:1.1rem;margin:0 0 8px}.card ul{margin:8px 0 0;padding-left:20px}.card code{background:#f2f4f7;border-radius:4px;padding:1px 6px;font-size:.9em}button{font:inherit;padding:8px 20px;border:none;border-radius:8px;background:#1d4ed8;color:#fff;cursor:pointer}button:hover{background:#1e40af}.app-footer{margin-top:40px;color:#98a2b3;font-size:.85rem;text-align:center}:root{font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Hiragino Sans,Noto Sans JP,sans-serif;line-height:1.6;color:#101828;background:#f8fafc}*{box-sizing:border-box}body{margin:0;min-height:100vh}