body { font-family: -apple-system, system-ui, sans-serif; background: #f8fafc; color: #0f172a; margin: 0; }
main { max-width: 440px; margin: 60px auto; padding: 28px; background: #fff; border-radius: 16px; box-shadow: 0 10px 30px rgba(15,23,42,.08); }
h1 { margin: 0 0 4px; }
p { color: #64748b; margin: 0 0 20px; }
.row { display: flex; gap: 10px; align-items: center; margin-bottom: 18px; }
input, select { padding: 10px; border: 1px solid #cbd5e1; border-radius: 8px; font-size: 1rem; }
input { width: 90px; }
output { display: block; font-size: 1.6rem; font-weight: 700; color: #0d9488; }