:root {
  color-scheme: light dark;
  --bg: #f7f8fb;
  --card-bg: #ffffff;
  --card-bg-dark: #0f1115;
  --text: #0f172a;
  --text-light: #5f6b84;
  --primary: #2b5fb8;        /* Saber 蓝 */
  --primary-dark: #1c3f7f;
  --accent: #cfa75b;         /* Saber 金 */
  --danger: #ff3b30;
  --success: #34c759;
  --border: rgba(12, 12, 13, 0.1);
  --shadow: 0 10px 32px rgba(16, 24, 40, 0.08);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0c0c0d;
    --card-bg: #141416;
    --card-bg-dark: #0f1115;
    --text: #f5f5f7;
    --text-light: #b0b0b7;
    --border: rgba(255, 255, 255, 0.12);
    --shadow: 0 12px 36px rgba(0, 0, 0, 0.45);
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "SF Pro Display", "SF Pro Text", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

.app-shell.is-locked {
  filter: blur(4px);
  pointer-events: none;
  user-select: none;
}

.login-overlay {
  position: fixed;
  inset: 0;
  background: radial-gradient(circle at 20% 20%, rgba(43, 95, 184, 0.12), transparent 40%),
    radial-gradient(circle at 80% 0%, rgba(207, 167, 91, 0.12), transparent 40%),
    rgba(6, 10, 20, 0.45);
  display: grid;
  place-items: center;
  padding: clamp(1rem, 4vw, 2rem);
  z-index: 1000;
  backdrop-filter: blur(18px);
}

.login-overlay.is-hidden {
  display: none;
}

.login-card {
  width: min(420px, 100%);
  background: var(--card-bg);
  border-radius: 1.15rem;
  border: 1px solid var(--border);
  box-shadow: 0 18px 44px rgba(16, 24, 40, 0.16);
  padding: 1.75rem;
  display: grid;
  gap: 1rem;
}

.login-card h2 {
  margin: 0;
}

.login-desc {
  margin: 0;
  color: var(--text-light);
}

.login-form {
  display: grid;
  gap: 0.6rem;
}

.login-form label {
  display: grid;
  gap: 0.35rem;
  font-weight: 600;
}

.login-form input {
  padding: 0.75rem 0.85rem;
  border-radius: 0.7rem;
  border: 1px solid var(--border);
  background: var(--card-bg);
  color: var(--text);
  font-size: 1rem;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.login-form input:focus-visible {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(10, 132, 255, 0.2);
}

.divider {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-light);
}

.divider::before,
.divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}

.login-hint {
  margin: 0;
  color: var(--text-light);
  font-size: 0.95rem;
}

.login-hint.success {
  color: var(--success);
}

.login-hint.warn {
  color: var(--danger);
}

.site-header {
  padding: 2.2rem clamp(1.2rem, 3vw, 3rem);
  display: flex;
  flex-wrap: wrap;
  gap: 1.2rem;
  align-items: center;
  justify-content: space-between;
  max-width: 1380px;
  margin: 0 auto;
}

.site-header h1 {
  margin: 0.2rem 0;
}

.subtitle {
  margin: 0;
  color: var(--text-light);
}

.eyebrow {
  margin: 0;
  font-size: 0.95rem;
  letter-spacing: 0.04em;
  color: var(--primary);
  font-weight: 700;
}

.meta-chip {
  padding: 0.55rem 1.05rem;
  border-radius: 12px;
  background: var(--card-bg);
  box-shadow: var(--shadow);
  font-weight: 600;
}

.status-banner {
  margin-top: 0.6rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  align-items: center;
  padding: 0.6rem 0.9rem;
  border-radius: 0.85rem;
  border: 1px solid var(--border);
  background: var(--card-bg);
  box-shadow: var(--shadow);
}

.status-chip {
  padding: 0.35rem 0.85rem;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.95rem;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.status-chip.guest {
  background: rgba(43, 95, 184, 0.15);
  color: var(--primary);
}

.status-chip.cloud {
  background: rgba(207, 167, 91, 0.2);
  color: var(--accent);
}

.status-chip.warn {
  background: rgba(255, 59, 48, 0.12);
  color: var(--danger);
}

.status-chip.neutral {
  background: rgba(17, 19, 32, 0.06);
  color: var(--text);
}

body.auth-guest .site-header {
  border-bottom: none;
}

body.auth-cloud .site-header {
  border-bottom: none;
}

.layout-grid {
  display: grid;
  grid-template-columns: minmax(0, 2fr) minmax(340px, 1fr);
  grid-template-areas:
    "quiz quiz"
    "auth stats"
    "modes stats"
    "history history";
  align-items: start;
  gap: 1.4rem;
  padding: 0 clamp(1.2rem, 3vw, 2.4rem) 3rem;
  max-width: 1380px;
  margin: 0 auto 2.2rem;
}

.quiz-panel {
  grid-area: quiz;
  min-height: 560px;
}

.auth-panel {
  grid-area: auth;
}

.mode-panel {
  grid-area: modes;
}

.stats-panel {
  grid-area: stats;
  position: sticky;
  top: 1rem;
  min-width: 280px;
}

.history-panel {
  grid-area: history;
}

.card {
  background: var(--card-bg);
  border-radius: 1rem;
  border: 1px solid var(--border);
  padding: 1.5rem;
  box-shadow: var(--shadow);
}

.card-header h2 {
  margin: 0;
}

.card-header p {
  margin: 0.5rem 0 0;
  color: var(--text-light);
}

.btn {
  appearance: none;
  -webkit-appearance: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 0.62rem 1.45rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  line-height: 1.2;
  min-height: 44px;
  max-height: 64px;
  transition: transform 0.12s ease, box-shadow 0.2s ease, background 0.2s ease, border-color 0.2s ease;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.06);
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  box-shadow: none;
}

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

.btn.primary:active,
.btn.primary:focus-visible {
  background: var(--primary-dark);
}

.btn.ghost {
  background: transparent;
  color: var(--primary);
  border: 1px solid rgba(10, 132, 255, 0.35);
}

.btn:hover:not(:disabled) {
  transform: translateY(-1px);
}

.auth-form {
  display: grid;
  gap: 0.6rem;
  margin-top: 1rem;
}

.auth-form label {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  font-weight: 600;
  color: var(--text);
}

.auth-form input {
  padding: 0.65rem 0.75rem;
  border-radius: 0.55rem;
  border: 1px solid var(--border);
  background: var(--card-bg);
  color: var(--text);
  font-size: 1rem;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.auth-form input:focus-visible {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(10, 132, 255, 0.18);
}

.auth-actions {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.auth-actions.stacked {
  flex-direction: column;
  align-items: stretch;
}

.mode-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 1rem;
}

.mode-tools {
  margin-top: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
}

.autosave-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.2rem 0.6rem;
  border: 1px dashed var(--border);
  border-radius: 0.75rem;
}

.autosave-controls label {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  color: var(--text-light);
  font-size: 0.95rem;
}

.autosave-controls select {
  padding: 0.35rem 0.6rem;
  border-radius: 0.5rem;
  border: 1px solid var(--border);
  background: var(--card-bg);
  color: var(--text);
}

.autosave-toggle input {
  accent-color: var(--primary);
}

.help-text {
  margin-top: 0.8rem;
  color: var(--text-light);
  font-size: 0.95rem;
}

.stats-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.8rem;
  margin: 1rem 0 0;
}

.stats-list dt {
  font-size: 0.9rem;
  color: var(--text-light);
}

.stats-list dd {
  margin: 0.2rem 0 0;
  font-size: 1.4rem;
  font-weight: 700;
}

.history-preview {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--text-light);
}

.question-container {
  margin-top: 1rem;
}

.question-header {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: space-between;
  align-items: center;
}

.question-number {
  font-weight: 700;
}

.question-tags {
  font-size: 0.95rem;
  color: var(--text-light);
}

.question-text {
  margin: 0.5rem 0 1rem;
  font-size: 1.15rem;
  line-height: 1.5;
}

.options-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.option-item {
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  padding: 0.8rem 1rem;
  display: flex;
  gap: 0.7rem;
  align-items: center;
}

.option-item.correct {
  border-color: var(--success);
  background: rgba(31, 154, 109, 0.12);
}

.option-item.wrong {
  border-color: var(--danger);
  background: rgba(223, 60, 75, 0.12);
}

.option-item label {
  flex: 1;
  cursor: pointer;
}

.action-row {
  margin-top: 1.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
}

.primary-actions {
  display: flex;
  gap: 0.8rem;
  flex: 1 1 260px;
  min-width: 260px;
  width: 100%;
}

.primary-actions .btn.stretch {
  flex: 1;
}

.btn.full {
  flex: 1 1 100%;
  width: 100%;
}

.is-hidden {
  display: none !important;
}

.feedback {
  margin-top: 1rem;
  font-weight: 600;
}

.feedback.correct {
  color: var(--success);
}

.feedback.wrong {
  color: var(--danger);
}

.history-table-wrapper {
  overflow-x: auto;
  max-height: 360px;
  scrollbar-color: rgba(0, 0, 0, 0.2) transparent;
}

.history-panel table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.history-panel th,
.history-panel td {
  padding: 0.6rem 0.4rem;
  border-bottom: 1px solid var(--border);
}

#toast {
  position: fixed;
  left: 50%;
  bottom: 1.5rem;
  transform: translateX(-50%);
  background: var(--card-bg-dark);
  color: #fff;
  padding: 0.75rem 1.2rem;
  border-radius: 999px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.2);
}

#toast.show {
  opacity: 1;
  transform: translate(-50%, -10px);
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 999;
  padding: 1rem;
}

.modal-card {
  background: var(--card-bg);
  border-radius: 0.75rem;
  border: 1px solid var(--border);
  max-width: 520px;
  width: min(520px, 100%);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.25);
  display: flex;
  flex-direction: column;
}

.modal-header {
  padding: 1rem 1.25rem 0.5rem;
}

.modal-body {
  padding: 0 1.25rem;
}

.modal-body textarea {
  width: 100%;
  min-height: 180px;
  resize: vertical;
  border-radius: 0.6rem;
  border: 1px solid var(--border);
  padding: 0.8rem;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.95rem;
  background: var(--card-bg);
  color: var(--text);
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.6rem;
  padding: 1rem 1.25rem 1.25rem;
}

@media (max-width: 768px) {
  .site-header {
    padding-bottom: 1rem;
  }

  .layout-grid {
    padding-inline: 1rem;
    grid-template-columns: 1fr;
    grid-template-areas:
      "quiz"
      "auth"
      "modes"
      "stats"
      "history";
  }

  .mode-actions,
  .mode-tools,
  .action-row,
  .primary-actions,
  .auth-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .primary-actions .btn.stretch {
    width: 100%;
    flex: 0 0 auto;
  }
}

@media (max-width: 1366px) {
  .layout-grid {
    grid-template-columns: 1fr;
    grid-template-areas:
      "quiz"
      "auth"
      "modes"
      "stats"
      "history";
  }

  .stats-panel {
    position: static;
  }
}