:root{--navy:#0b1f3a;--ink:#1b2430;--muted:#5b6675;--line:#e3e7ee;--bg:#f6f8fb;--card:#fff;--accent:#1f6feb;--warn:#9a3412}*{box-sizing:border-box}html,body{margin:0;padding:0}body{background:var(--bg);color:var(--ink);font:15px/1.55 -apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif}.band{background:var(--navy);color:#fff;letter-spacing:.2px;padding:18px 24px;font-weight:600}.band small{opacity:.75;font-size:13px;font-weight:400;display:block}main{max-width:640px;margin:32px auto;padding:0 16px}.card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:24px}h1{margin:0 0 8px;font-size:20px}p{color:var(--muted);margin:8px 0}.problem{color:var(--warn);background:#fff7ed;border-color:#fed7aa}.button{background:var(--accent);color:#fff;cursor:pointer;border:0;border-radius:8px;padding:10px 16px;font-size:15px;font-weight:600;text-decoration:none;display:inline-block}.button.secondary{color:var(--ink);border:1px solid var(--line);background:#fff}.row{flex-wrap:wrap;gap:12px;margin-top:16px;display:flex}