body{font-family:system-ui,sans-serif;background:#f4f6f9;margin:0}main{max-width:720px;margin:50px auto;padding:20px}.card{background:#fff;padding:24px;border-radius:14px;box-shadow:0 8px 30px #0001}input,button{display:block;width:100%;box-sizing:border-box;padding:12px;margin:10px 0;border:1px solid #ccd;border-radius:8px}button{cursor:pointer;font-weight:700}pre{white-space:pre-wrap}