*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0a0c14;
  --surface: #141824;
  --surface2: #1c2235;
  --border: #2a3050;
  --text: #e8eaf4;
  --text2: #7b82a0;
  --accent: #6c5ce7;
  --accent2: #a29bfe;
  --green: #00b894;
  --green-bg: rgba(0,184,148,0.12);
  --yellow: #fdcb6e;
  --yellow-bg: rgba(253,203,110,0.12);
  --red: #e17055;
  --red-bg: rgba(225,112,85,0.12);
  --radius: 20px;
  --radius-sm: 14px;
}

html { font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ===== Layout ===== */
.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 24px 24px 120px;
}
@media (min-width: 600px) {
  .container { padding: 40px 40px 120px; }
}

/* ===== Header ===== */
.header {
  text-align: center;
  padding: 72px 0 24px;
}
.header h1 {
  font-size: 40px;
  font-weight: 900;
  background: linear-gradient(135deg, #a29bfe 0%, #6c5ce7 50%, #fd79a8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -1px;
}
.header p {
  color: var(--text2);
  font-size: 16px;
  margin-top: 8px;
  letter-spacing: 2px;
}

/* ===== Stats bar ===== */
.stats-bar {
  display: flex;
  justify-content: center;
  gap: 48px;
  padding: 20px 0;
  margin-bottom: 32px;
  border-bottom: 1px solid var(--border);
}
.stat { text-align: center; }
.stat-value {
  font-size: 28px;
  font-weight: 800;
  color: var(--accent2);
}
.stat-label {
  font-size: 13px;
  color: var(--text2);
  margin-top: 2px;
}

/* ===== Cards ===== */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 20px;
}
@media (max-width: 500px) {
  .card { padding: 20px 18px; }
}

/* ===== Setup screen ===== */
.setup-section { margin-bottom: 32px; }
.setup-section:last-child { margin-bottom: 0; }
.setup-section h3 {
  font-size: 15px;
  color: var(--text2);
  margin-bottom: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.grade-grid, .subject-grid {
  display: grid;
  gap: 10px;
}
.grade-grid { grid-template-columns: repeat(3, 1fr); }
.subject-grid { grid-template-columns: repeat(3, 1fr); }
@media (min-width: 600px) {
  .subject-grid { grid-template-columns: repeat(5, 1fr); }
}

.chip {
  padding: 14px 8px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: var(--surface2);
  color: var(--text2);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  text-align: center;
  user-select: none;
}
.chip:hover { border-color: #3d4570; background: #222840; }
.chip:active { transform: scale(0.96); }
.chip.active {
  border-color: var(--accent);
  background: rgba(108, 92, 231, 0.18);
  color: var(--accent2);
}

/* ===== Mode selector ===== */
.mode-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.mode-card {
  padding: 24px 16px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: var(--surface2);
  cursor: pointer;
  transition: all 0.2s;
  text-align: center;
}
.mode-card:hover { border-color: #3d4570; }
.mode-card:active { transform: scale(0.97); }
.mode-card.active {
  border-color: var(--accent);
  background: rgba(108, 92, 231, 0.18);
}
.mode-card .mode-icon { font-size: 36px; margin-bottom: 8px; }
.mode-card .mode-name { font-size: 17px; font-weight: 700; color: var(--text); }
.mode-card .mode-desc { font-size: 13px; color: var(--text2); margin-top: 4px; }

/* ===== Buttons ===== */
.btn {
  width: 100%;
  padding: 18px;
  border-radius: var(--radius-sm);
  border: none;
  font-size: 17px;
  font-weight: 800;
  cursor: pointer;
  transition: all 0.2s;
  letter-spacing: 0.5px;
}
.btn:active { transform: scale(0.98); }
.btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  transform: none;
}
.btn-primary {
  background: linear-gradient(135deg, var(--accent), #8b7cf0);
  color: #fff;
  box-shadow: 0 4px 24px rgba(108, 92, 231, 0.3);
}
.btn-primary:hover:not(:disabled) {
  box-shadow: 0 6px 32px rgba(108, 92, 231, 0.45);
}
.btn-ghost {
  background: var(--surface2);
  color: var(--text);
  border: 2px solid var(--border);
}

/* ===== Question display ===== */
.question-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
}
.question-badge {
  display: inline-block;
  padding: 5px 14px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 700;
}
.difficulty-1, .difficulty-2 { background: var(--green-bg); color: var(--green); }
.difficulty-3 { background: var(--yellow-bg); color: var(--yellow); }
.difficulty-4, .difficulty-5 { background: var(--red-bg); color: var(--red); }

.question-num {
  font-size: 13px;
  color: var(--text2);
  font-weight: 600;
}

.question-text {
  font-size: 18px;
  line-height: 2;
  color: var(--text);
  white-space: pre-wrap;
}
@media (min-width: 600px) {
  .question-text { font-size: 20px; }
}

/* ===== Choice groups ===== */
.choice-group { margin-bottom: 4px; }
.choice-label {
  font-size: 15px;
  font-weight: 700;
  color: var(--accent2);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.choice-label::before {
  content: '';
  width: 4px;
  height: 18px;
  background: var(--accent);
  border-radius: 2px;
  flex-shrink: 0;
}
.choice-options { display: flex; flex-direction: column; gap: 10px; }
.choice-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: var(--surface2);
  cursor: pointer;
  transition: all 0.15s;
  user-select: none;
}
.choice-item:hover { border-color: #3d4570; background: #222840; }
.choice-item:active { transform: scale(0.98); }
.choice-item.selected {
  border-color: var(--accent);
  background: rgba(108, 92, 231, 0.18);
}
.choice-letter {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 800;
  background: var(--border);
  color: var(--text2);
  flex-shrink: 0;
  transition: all 0.15s;
}
.choice-item.selected .choice-letter {
  background: var(--accent);
  color: #fff;
}
.choice-text {
  font-size: 15px;
  color: var(--text);
  line-height: 1.6;
}

/* ===== Feedback ===== */
.eval-item {
  padding: 18px 20px;
  border-radius: var(--radius-sm);
  margin-bottom: 12px;
}
.eval-item:last-child { margin-bottom: 0; }
.eval-item.correct { background: var(--green-bg); border-left: 4px solid var(--green); }
.eval-item.wrong { background: var(--red-bg); border-left: 4px solid var(--red); }

.eval-label {
  font-size: 15px;
  font-weight: 800;
  margin-bottom: 6px;
}
.eval-item.correct .eval-label { color: var(--green); }
.eval-item.wrong .eval-label { color: var(--red); }

.eval-comment {
  font-size: 14px;
  color: var(--text);
  line-height: 1.7;
}

.correct-analysis {
  background: var(--surface2);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
}
.correct-analysis h4 {
  font-size: 15px;
  color: var(--accent2);
  margin-bottom: 12px;
  font-weight: 700;
}
.correct-analysis p {
  font-size: 15px;
  color: var(--text);
  line-height: 1.8;
}

.score-display {
  text-align: center;
  padding: 32px 0 16px;
}
.score-number {
  font-size: 72px;
  font-weight: 900;
  line-height: 1;
}
.score-number.perfect {
  background: linear-gradient(135deg, var(--green), #55efc4);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.score-number.good {
  background: linear-gradient(135deg, var(--accent2), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.score-number.bad {
  background: linear-gradient(135deg, var(--red), #fab1a0);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.score-label {
  font-size: 15px;
  color: var(--text2);
  margin-top: 8px;
}

.score-tip {
  padding: 16px 20px;
  background: rgba(108,92,231,0.1);
  border-radius: var(--radius-sm);
  font-size: 15px;
  color: var(--accent2);
  line-height: 1.7;
}

/* ===== Challenge summary ===== */
.challenge-summary-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
}
.challenge-summary-item:last-child { border-bottom: none; }
.challenge-q-num {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  font-weight: 800;
  flex-shrink: 0;
}
.challenge-q-num.high { background: var(--green-bg); color: var(--green); }
.challenge-q-num.mid { background: var(--yellow-bg); color: var(--yellow); }
.challenge-q-num.low { background: var(--red-bg); color: var(--red); }
.challenge-q-text {
  font-size: 14px;
  color: var(--text2);
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.challenge-q-score { font-size: 18px; font-weight: 800; color: var(--text); }

/* ===== Loading ===== */
.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 80px 0;
  gap: 20px;
}
.spinner {
  width: 44px;
  height: 44px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text { font-size: 16px; color: var(--text2); }
.loading-progress { font-size: 13px; color: var(--text2); }

/* ===== Progress bar ===== */
.progress-bar {
  display: flex;
  gap: 8px;
  margin-bottom: 24px;
}
.progress-dot {
  flex: 1;
  height: 6px;
  border-radius: 3px;
  background: var(--border);
  transition: background 0.3s;
}
.progress-dot.done { background: var(--green); }
.progress-dot.current { background: var(--accent); }

/* ===== Screens ===== */
.screen { display: none; }
.screen.active { display: block; }

/* ===== Button row ===== */
.btn-row {
  display: flex;
  gap: 12px;
  margin-top: 12px;
}
.btn-row .btn { flex: 1; }

/* ===== Step indicator ===== */
.step-indicator {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-bottom: 20px;
}
.step-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
  transition: all 0.3s;
}
.step-dot.active {
  background: var(--accent);
  box-shadow: 0 0 8px rgba(108, 92, 231, 0.5);
}
.step-dot.done {
  background: var(--green);
}

.choice-step-num {
  font-size: 12px;
  color: var(--text2);
  margin-bottom: 8px;
  font-weight: 600;
  letter-spacing: 1px;
}

/* Choice card transition */
#choiceCard {
  transition: opacity 0.15s ease, transform 0.15s ease;
}
#choiceCard.swapping {
  opacity: 0;
  transform: translateX(30px);
}

/* ===== Animations ===== */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}
.fade-in { animation: fadeIn 0.3s ease-out; }

/* ===== Buffer indicator ===== */
.buffer-indicator {
  position: fixed;
  bottom: 20px;
  right: 20px;
  padding: 8px 14px;
  border-radius: 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 12px;
  color: var(--text2);
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
  z-index: 100;
}
.buffer-indicator.visible { opacity: 1; }

/* ===== Setup 一屏铺满模式（仅配置页） ===== */
body[data-screen="setupScreen"] {
  overflow: hidden;
}
body[data-screen="setupScreen"] .container {
  max-width: 1180px;
  height: 100dvh;
  padding: clamp(14px, 2.2vh, 26px) clamp(18px, 3.2vw, 48px) clamp(14px, 2vh, 24px);
  display: flex;
  flex-direction: column;
}
body[data-screen="setupScreen"] .header {
  padding: 0;
  margin-bottom: clamp(8px, 1vh, 14px);
}
body[data-screen="setupScreen"] .header h1 {
  font-size: clamp(34px, 4.8vw, 56px);
  line-height: 1.05;
}
body[data-screen="setupScreen"] .header p {
  font-size: clamp(14px, 1.7vw, 18px);
  margin-top: 6px;
  letter-spacing: 1.2px;
}
body[data-screen="setupScreen"] .stats-bar {
  gap: clamp(36px, 5vw, 72px);
  padding: 10px 0 12px;
  margin-bottom: clamp(10px, 1.4vh, 18px);
}
body[data-screen="setupScreen"] .stat-value {
  font-size: clamp(28px, 3.3vw, 40px);
}
body[data-screen="setupScreen"] .stat-label {
  font-size: 13px;
}
body[data-screen="setupScreen"] #setupScreen.active {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
}
body[data-screen="setupScreen"] #setupScreen > .card {
  flex: 1;
  min-height: 0;
  margin-bottom: clamp(10px, 1.5vh, 18px);
  padding: clamp(18px, 2.2vh, 28px) clamp(20px, 2.8vw, 34px);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  grid-auto-rows: min-content;
  gap: clamp(10px, 1.4vh, 16px) clamp(14px, 1.8vw, 22px);
  align-content: start;
  overflow: hidden;
}
body[data-screen="setupScreen"] .setup-section {
  margin-bottom: 0;
  min-height: 0;
}
body[data-screen="setupScreen"] #setupScreen > .card .setup-section:nth-child(1) { grid-column: 1; }
body[data-screen="setupScreen"] #setupScreen > .card .setup-section:nth-child(2) { grid-column: 2; }
body[data-screen="setupScreen"] #setupScreen > .card .setup-section:nth-child(3) { grid-column: 1 / -1; }
body[data-screen="setupScreen"] .setup-section h3 {
  font-size: clamp(13px, 1.6vw, 16px);
  margin-bottom: clamp(10px, 1.2vh, 14px);
}
body[data-screen="setupScreen"] .grade-grid,
body[data-screen="setupScreen"] .subject-grid {
  gap: clamp(8px, 1vh, 12px);
}
body[data-screen="setupScreen"] .grade-grid {
  grid-template-columns: repeat(5, minmax(0, 1fr));
}
body[data-screen="setupScreen"] .subject-grid {
  grid-template-columns: repeat(5, minmax(0, 1fr));
}
body[data-screen="setupScreen"] .chip {
  padding: clamp(8px, 1.2vh, 13px) 6px;
  font-size: clamp(13px, 1.35vw, 15px);
}
body[data-screen="setupScreen"] .chip small {
  font-size: clamp(10px, 1.1vw, 12px) !important;
  line-height: 1.25;
}
body[data-screen="setupScreen"] .mode-grid {
  gap: clamp(10px, 1.4vh, 14px);
}
body[data-screen="setupScreen"] .mode-card {
  padding: clamp(10px, 1.2vh, 14px) 12px;
}
body[data-screen="setupScreen"] .mode-card .mode-icon {
  font-size: clamp(20px, 2.4vw, 28px);
  margin-bottom: 4px;
}
body[data-screen="setupScreen"] .mode-card .mode-name {
  font-size: clamp(15px, 1.7vw, 18px);
}
body[data-screen="setupScreen"] .mode-card .mode-desc {
  font-size: clamp(11px, 1.2vw, 13px);
  margin-top: 2px;
}
body[data-screen="setupScreen"] #startBtn {
  flex-shrink: 0;
  padding: clamp(12px, 1.7vh, 16px);
  font-size: clamp(16px, 1.9vw, 20px);
  margin-top: 0;
}

@media (max-height: 860px) {
  body[data-screen="setupScreen"] .container {
    padding: 12px 18px 14px;
  }
  body[data-screen="setupScreen"] .header h1 {
    font-size: clamp(30px, 4.2vw, 44px);
  }
  body[data-screen="setupScreen"] .header p {
    font-size: 14px;
    margin-top: 4px;
  }
  body[data-screen="setupScreen"] .stats-bar {
    gap: 30px;
    margin-bottom: 10px;
  }
  body[data-screen="setupScreen"] .stat-value {
    font-size: 24px;
  }
  body[data-screen="setupScreen"] #setupScreen > .card {
    padding: 14px 18px;
    gap: 8px 12px;
  }
  body[data-screen="setupScreen"] .setup-section {
    margin-bottom: 0;
  }
  body[data-screen="setupScreen"] .chip {
    padding: 7px 5px;
    font-size: 13px;
  }
  body[data-screen="setupScreen"] .mode-card {
    padding: 8px 10px;
  }
  body[data-screen="setupScreen"] #startBtn {
    padding: 10px;
    font-size: 15px;
  }
}

@media (max-height: 760px) and (min-width: 901px) {
  body[data-screen="setupScreen"] .container {
    padding: 10px 16px 12px;
  }
  body[data-screen="setupScreen"] .header {
    margin-bottom: 6px;
  }
  body[data-screen="setupScreen"] .header h1 {
    font-size: 30px;
  }
  body[data-screen="setupScreen"] .header p {
    font-size: 13px;
    margin-top: 2px;
  }
  body[data-screen="setupScreen"] .stats-bar {
    gap: 24px;
    padding: 6px 0 8px;
    margin-bottom: 8px;
  }
  body[data-screen="setupScreen"] .stat-value {
    font-size: 22px;
  }
  body[data-screen="setupScreen"] #setupScreen > .card {
    padding: 10px 14px;
    gap: 6px 10px;
  }
  body[data-screen="setupScreen"] .setup-section h3 {
    margin-bottom: 6px;
  }
  body[data-screen="setupScreen"] .grade-grid,
  body[data-screen="setupScreen"] .subject-grid {
    gap: 6px;
  }
  body[data-screen="setupScreen"] .chip {
    padding: 6px 4px;
    font-size: 12px;
  }
  body[data-screen="setupScreen"] .chip small {
    font-size: 10px !important;
  }
  body[data-screen="setupScreen"] .mode-grid {
    gap: 8px;
  }
  body[data-screen="setupScreen"] .mode-card {
    padding: 7px 8px;
  }
  body[data-screen="setupScreen"] .mode-card .mode-icon {
    font-size: 18px;
    margin-bottom: 2px;
  }
  body[data-screen="setupScreen"] .mode-card .mode-name {
    font-size: 14px;
  }
  body[data-screen="setupScreen"] .mode-card .mode-desc {
    font-size: 11px;
    margin-top: 1px;
  }
  body[data-screen="setupScreen"] #startBtn {
    padding: 9px;
    font-size: 15px;
  }
}

@media (max-width: 900px) {
  body[data-screen="setupScreen"] .container {
    padding: 10px 10px 12px;
  }
  body[data-screen="setupScreen"] .header h1 {
    font-size: clamp(24px, 7vw, 34px);
  }
  body[data-screen="setupScreen"] .header p {
    font-size: 12px;
    margin-top: 2px;
  }
  body[data-screen="setupScreen"] .stats-bar {
    gap: 16px;
    padding: 6px 0 8px;
    margin-bottom: 8px;
  }
  body[data-screen="setupScreen"] .stat-value {
    font-size: 20px;
  }
  body[data-screen="setupScreen"] #setupScreen > .card {
    grid-template-columns: 1fr;
    gap: 8px;
    padding: 10px 12px;
  }
  body[data-screen="setupScreen"] #setupScreen > .card .setup-section:nth-child(1),
  body[data-screen="setupScreen"] #setupScreen > .card .setup-section:nth-child(2),
  body[data-screen="setupScreen"] #setupScreen > .card .setup-section:nth-child(3) {
    grid-column: 1;
  }
  body[data-screen="setupScreen"] .grade-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  body[data-screen="setupScreen"] .subject-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  body[data-screen="setupScreen"] .mode-grid {
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }
  body[data-screen="setupScreen"] .chip {
    padding: 6px 4px;
    font-size: 12px;
  }
  body[data-screen="setupScreen"] .chip small {
    font-size: 10px !important;
  }
  body[data-screen="setupScreen"] .mode-card {
    padding: 7px 8px;
  }
  body[data-screen="setupScreen"] .mode-card .mode-icon {
    font-size: 18px;
    margin-bottom: 2px;
  }
  body[data-screen="setupScreen"] .mode-card .mode-name {
    font-size: 13px;
  }
  body[data-screen="setupScreen"] .mode-card .mode-desc {
    font-size: 10px;
    margin-top: 1px;
  }
  body[data-screen="setupScreen"] #startBtn {
    padding: 10px;
    font-size: 15px;
  }
}