:root {
  color-scheme: light dark;
  --bg: #f8fafc;
  --card: rgba(255, 255, 255, 0.92);
  --text: #0f172a;
  --muted: #64748b;
  --border: #e2e8f0;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --danger: #dc2626;
  --shadow: 0 22px 70px rgba(15, 23, 42, 0.10);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #020617;
    --card: rgba(15, 23, 42, 0.88);
    --text: #e5e7eb;
    --muted: #94a3b8;
    --border: #1e293b;
    --primary: #60a5fa;
    --primary-dark: #3b82f6;
    --shadow: 0 22px 70px rgba(0, 0, 0, 0.34);
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  background:
    radial-gradient(circle at top left, rgba(37, 99, 235, 0.18), transparent 32rem),
    radial-gradient(circle at bottom right, rgba(14, 165, 233, 0.15), transparent 28rem),
    var(--bg);
  color: var(--text);
}

.page {
  width: min(920px, calc(100% - 32px));
  margin: 0 auto;
  padding: 48px 0;
}

.hero { margin-bottom: 24px; }

.brand {
  display: flex;
  align-items: center;
  gap: 18px;
}

.logo {
  width: 64px;
  height: 64px;
  display: grid;
  place-items: center;
  border-radius: 20px;
  background: linear-gradient(135deg, #2563eb, #0ea5e9);
  color: #fff;
  font-size: 22px;
  font-weight: 900;
  letter-spacing: -0.04em;
  box-shadow: 0 18px 50px rgba(37, 99, 235, 0.30);
}

h1 {
  margin: 0;
  font-size: clamp(28px, 5vw, 46px);
  line-height: 1.1;
  letter-spacing: -0.06em;
}

.hero p,
.note-card p {
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.8;
}

.card {
  border: 1px solid var(--border);
  background: var(--card);
  box-shadow: var(--shadow);
  border-radius: 28px;
  padding: 24px;
  backdrop-filter: blur(18px);
}

.generator-card { margin-bottom: 18px; }

.label,
.settings-grid span {
  display: block;
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

.secret-input {
  width: 100%;
  min-height: 128px;
  resize: vertical;
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 16px;
  outline: none;
  background: color-mix(in srgb, var(--card), var(--bg) 35%);
  color: var(--text);
  font-size: 15px;
  line-height: 1.65;
  transition: border-color 0.2s, box-shadow 0.2s, filter 0.2s;
}

.secret-input.is-hidden {
  filter: blur(5px);
}

.secret-input:focus,
select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--primary), transparent 80%);
}

.settings-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 16px;
}

select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 12px 14px;
  background: color-mix(in srgb, var(--card), var(--bg) 35%);
  color: var(--text);
  outline: none;
}

.meta-box {
  margin-top: 16px;
  padding: 12px 14px;
  border: 1px dashed var(--border);
  border-radius: 16px;
  color: var(--muted);
  line-height: 1.7;
  font-size: 14px;
}

.hidden { display: none; }

.code-box {
  margin-top: 20px;
  padding: 22px;
  border-radius: 22px;
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.10), rgba(14, 165, 233, 0.08));
  border: 1px solid color-mix(in srgb, var(--primary), transparent 72%);
}

.code-label {
  color: var(--muted);
  font-size: 14px;
  font-weight: 800;
}

.code-output {
  margin-top: 8px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: clamp(48px, 12vw, 76px);
  font-weight: 900;
  line-height: 1;
  letter-spacing: 0.08em;
}

.countdown-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 14px;
  color: var(--muted);
  font-weight: 700;
}

.progress-wrap {
  height: 10px;
  margin-top: 10px;
  overflow: hidden;
  border-radius: 999px;
  background: color-mix(in srgb, var(--primary), transparent 86%);
}

.progress-bar {
  height: 100%;
  width: 0%;
  border-radius: inherit;
  background: linear-gradient(90deg, #2563eb, #0ea5e9);
  transition: width 0.25s linear;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

button {
  border: 0;
  border-radius: 15px;
  padding: 12px 16px;
  font-size: 15px;
  font-weight: 800;
  cursor: pointer;
  transition: transform 0.15s, opacity 0.15s, background 0.15s;
}

button:active { transform: scale(0.98); }
button:disabled { opacity: 0.48; cursor: not-allowed; }

.primary {
  background: var(--primary);
  color: #fff;
}
.primary:hover { background: var(--primary-dark); }

.secondary {
  background: color-mix(in srgb, var(--primary), transparent 84%);
  color: var(--text);
}

.ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted);
}

.message {
  min-height: 22px;
  margin: 14px 0 0;
  color: var(--muted);
  font-weight: 700;
}
.message.error { color: var(--danger); }
.message.ok { color: #16a34a; }

.note-card h2 {
  margin: 0;
  font-size: 20px;
}

@media (max-width: 680px) {
  .page { width: min(100% - 22px, 920px); padding: 26px 0; }
  .brand { align-items: flex-start; }
  .logo { width: 54px; height: 54px; border-radius: 17px; }
  .card { padding: 18px; border-radius: 22px; }
  .settings-grid { grid-template-columns: 1fr; }
  .actions button { flex: 1 1 100%; }
}