:root {
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #111827;
  --muted: #6b7280;
  --border: #e5e7eb;
  --shadow: 0 10px 25px rgba(0, 0, 0, 0.06);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
}

.container {
  max-width: 720px;
  margin: 32px auto;
  padding: 0 16px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  box-shadow: var(--shadow);
  padding: 20px;
}

h1 {
  font-size: 28px;
  margin: 0 0 8px;
  letter-spacing: -0.02em;
}

.lede {
  margin: 0 0 18px;
  color: var(--muted);
}

.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}

@media (min-width: 640px) {
  .grid {
    grid-template-columns: 1fr 1fr;
  }
}

label {
  display: block;
  font-weight: 600;
  font-size: 14px;
  margin-bottom: 6px;
}

.hint {
  display: block;
  font-size: 12px;
  color: var(--muted);
  margin-top: 6px;
}

input {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 16px;
}

.actions {
  margin-top: 14px;
}

button {
  width: 100%;
  padding: 12px;
  border: 0;
  border-radius: 10px;
  font-weight: 700;
  font-size: 16px;
  background: #111827;
  color: white;
  cursor: pointer;
}

.result {
  margin-top: 16px;
  padding: 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: #fafafa;
  font-weight: 700;
}

.result.success {
  background: rgba(16,185,129,0.08);
}

.result.error {
  background: rgba(239,68,68,0.08);
}