/* ===== RESET & BASE ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --black: #1a1a1a;
  --red: #DD0000;
  --gold: #FFCE00;
  --gold-dark: #e6b800;
  --bg: #f5f5f5;
  --card-bg: #ffffff;
  --text: #222222;
  --text-light: #666666;
  --border: #e0e0e0;
  --green: #2e7d32;
  --green-light: #e8f5e9;
  --red-light: #ffebee;
  --shadow: 0 2px 8px rgba(0,0,0,0.10);
  --shadow-lg: 0 4px 20px rgba(0,0,0,0.13);
  --radius: 10px;
  --radius-lg: 16px;
  --transition: 0.2s ease;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

/* ===== HEADER ===== */
header {
  background: var(--black);
  color: #fff;
  padding: 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 12px rgba(0,0,0,0.25);
}

.header-inner {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  gap: 16px;
  height: 60px;
}

.header-flag {
  display: flex;
  flex-direction: column;
  width: 32px;
  height: 22px;
  border-radius: 3px;
  overflow: hidden;
  flex-shrink: 0;
}
.header-flag span {
  flex: 1;
}
.header-flag span:nth-child(1) { background: #000; }
.header-flag span:nth-child(2) { background: var(--red); }
.header-flag span:nth-child(3) { background: var(--gold); }

header h1 {
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.5px;
  color: #fff;
  flex: 1;
}
header h1 span {
  color: var(--gold);
}

.header-subtitle {
  font-size: 0.78rem;
  color: #aaa;
  white-space: nowrap;
}

/* ===== MAIN LAYOUT ===== */
main {
  max-width: 860px;
  margin: 0 auto;
  padding: 28px 16px 60px;
}

/* ===== SETUP SCREEN ===== */
#setup-screen {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.setup-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 28px 32px;
}

.setup-card h2 {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 18px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--gold);
  display: flex;
  align-items: center;
  gap: 8px;
}

.setup-card h2 .icon {
  font-size: 1.1rem;
}

/* State selector */
.state-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.state-row label {
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-light);
  white-space: nowrap;
}

#state-select {
  flex: 1;
  min-width: 200px;
  padding: 10px 14px;
  border: 2px solid var(--border);
  border-radius: 8px;
  font-size: 0.95rem;
  background: #fff;
  color: var(--text);
  cursor: pointer;
  transition: border-color var(--transition);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%23666' stroke-width='1.8' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 34px;
}

#state-select:focus {
  outline: none;
  border-color: var(--gold);
  box-shadow: 0 0 0 3px rgba(255,206,0,0.2);
}

/* Mode buttons */
.mode-buttons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.mode-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 24px 16px;
  border: 2px solid var(--border);
  border-radius: var(--radius-lg);
  background: #fff;
  cursor: pointer;
  transition: all var(--transition);
  text-align: center;
}

.mode-btn:hover {
  border-color: var(--gold);
  background: #fffbea;
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.mode-btn .mode-icon {
  font-size: 2.2rem;
}

.mode-btn .mode-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--black);
}

.mode-btn .mode-desc {
  font-size: 0.78rem;
  color: var(--text-light);
  line-height: 1.4;
}

.mode-btn.primary {
  border-color: var(--red);
  background: linear-gradient(135deg, #fff5f5 0%, #fff 100%);
}
.mode-btn.primary:hover {
  border-color: var(--red);
  background: #fff0f0;
}
.mode-btn.primary .mode-title { color: var(--red); }

/* Practice filters */
.practice-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

.practice-filters label {
  font-size: 0.9rem;
  color: var(--text-light);
  font-weight: 500;
  margin-right: 4px;
}

.filter-btn {
  padding: 6px 14px;
  border: 2px solid var(--border);
  border-radius: 20px;
  background: #fff;
  font-size: 0.82rem;
  cursor: pointer;
  transition: all var(--transition);
  font-weight: 500;
  color: var(--text);
}

.filter-btn:hover {
  border-color: var(--gold);
  background: #fffbea;
}

.filter-btn.active {
  border-color: var(--gold-dark);
  background: var(--gold);
  color: var(--black);
}

/* Info bar */
.info-bar {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.info-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--text-light);
}

.info-item strong {
  color: var(--text);
  font-weight: 600;
}

.info-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--gold);
  flex-shrink: 0;
}

/* ===== QUIZ SCREEN ===== */
#quiz-screen {
  display: none;
  flex-direction: column;
  gap: 20px;
}

/* Quiz header bar */
.quiz-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.quiz-mode-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 600;
}

.quiz-mode-badge.mock {
  background: #ffeaea;
  color: var(--red);
  border: 1.5px solid #ffbbbb;
}

.quiz-mode-badge.practice {
  background: #fffbea;
  color: #b8860b;
  border: 1.5px solid var(--gold);
}

.quiz-counter {
  font-size: 0.9rem;
  color: var(--text-light);
}

.quiz-counter strong {
  color: var(--text);
  font-size: 1.0rem;
}

.btn-exit {
  padding: 6px 14px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  background: #fff;
  font-size: 0.82rem;
  cursor: pointer;
  color: var(--text-light);
  transition: all var(--transition);
}
.btn-exit:hover {
  border-color: var(--red);
  color: var(--red);
  background: #fff5f5;
}

/* Progress bar */
.progress-wrap {
  background: var(--border);
  border-radius: 10px;
  height: 8px;
  overflow: hidden;
  position: relative;
}

.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--gold) 0%, var(--gold-dark) 100%);
  border-radius: 10px;
  transition: width 0.4s ease;
  position: relative;
}

.progress-bar::after {
  content: '';
  position: absolute;
  top: 0; right: 0;
  width: 4px; height: 100%;
  background: rgba(255,255,255,0.5);
  border-radius: 0 10px 10px 0;
}

.progress-label {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  color: var(--text-light);
  margin-top: 4px;
}

/* Question card */
.question-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: box-shadow var(--transition);
}

.question-card:hover {
  box-shadow: var(--shadow-lg);
}

.question-header {
  background: var(--black);
  color: #fff;
  padding: 16px 24px;
  display: flex;
  align-items: flex-start;
  gap: 14px;
}

.question-num {
  background: var(--gold);
  color: var(--black);
  font-weight: 800;
  font-size: 0.85rem;
  padding: 3px 10px;
  border-radius: 12px;
  white-space: nowrap;
  flex-shrink: 0;
  margin-top: 2px;
}

.question-category-tag {
  font-size: 0.72rem;
  padding: 2px 8px;
  border-radius: 10px;
  background: rgba(255,255,255,0.12);
  color: #ccc;
  white-space: nowrap;
  flex-shrink: 0;
  margin-top: 4px;
}

.question-text {
  font-size: 1.0rem;
  line-height: 1.65;
  font-weight: 400;
  flex: 1;
}

/* Options */
.options-list {
  padding: 20px 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  list-style: none;
}

.option-item {
  position: relative;
}

.option-item input[type="radio"] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.option-label {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 16px;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--transition);
  font-size: 0.92rem;
  line-height: 1.5;
  background: #fff;
  user-select: none;
}

.option-label:hover {
  border-color: var(--gold);
  background: #fffbf0;
}

.option-key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--bg);
  border: 1.5px solid var(--border);
  font-weight: 700;
  font-size: 0.82rem;
  flex-shrink: 0;
  transition: all var(--transition);
  color: var(--text-light);
}

.option-item input[type="radio"]:checked + .option-label {
  border-color: var(--gold-dark);
  background: #fffbea;
}

.option-item input[type="radio"]:checked + .option-label .option-key {
  background: var(--gold);
  border-color: var(--gold-dark);
  color: var(--black);
}

/* Answer revealed states */
.option-item.correct .option-label {
  border-color: var(--green) !important;
  background: var(--green-light) !important;
}

.option-item.correct .option-label .option-key {
  background: var(--green) !important;
  border-color: var(--green) !important;
  color: #fff !important;
}

.option-item.wrong .option-label {
  border-color: var(--red) !important;
  background: var(--red-light) !important;
}

.option-item.wrong .option-label .option-key {
  background: var(--red) !important;
  border-color: var(--red) !important;
  color: #fff !important;
}

.option-item.disabled .option-label {
  cursor: default;
  pointer-events: none;
}

/* Explanation */
.explanation-box {
  margin: 0 24px 20px;
  padding: 14px 16px;
  background: #f0f7ff;
  border-left: 4px solid #1976d2;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 0.88rem;
  line-height: 1.65;
  color: #1a3a5c;
  display: none;
}

.explanation-box.visible {
  display: block;
  animation: fadeIn 0.25s ease;
}

.explanation-box strong {
  display: block;
  margin-bottom: 4px;
  color: #1565c0;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Quiz action buttons */
.quiz-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 20px;
  border-radius: 8px;
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: 2px solid transparent;
  white-space: nowrap;
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none !important;
}

.btn-prev {
  background: #fff;
  border-color: var(--border);
  color: var(--text);
}
.btn-prev:hover:not(:disabled) {
  border-color: #aaa;
  background: #f5f5f5;
}

.btn-next {
  background: var(--black);
  color: #fff;
  border-color: var(--black);
}
.btn-next:hover:not(:disabled) {
  background: #333;
  transform: translateX(2px);
}

.btn-check {
  background: var(--gold);
  color: var(--black);
  border-color: var(--gold-dark);
}
.btn-check:hover:not(:disabled) {
  background: var(--gold-dark);
  transform: translateY(-1px);
  box-shadow: 0 3px 10px rgba(255,206,0,0.4);
}

.btn-finish {
  background: var(--red);
  color: #fff;
  border-color: var(--red);
}
.btn-finish:hover:not(:disabled) {
  background: #bb0000;
  transform: translateY(-1px);
  box-shadow: 0 3px 10px rgba(221,0,0,0.3);
}

.btn-restart {
  background: var(--black);
  color: #fff;
  border-color: var(--black);
}
.btn-restart:hover {
  background: #333;
}

.spacer { flex: 1; }

/* Answered dots */
.answered-dots {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  padding: 16px 24px;
  border-top: 1px solid var(--border);
}

.dot {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  border: 2px solid var(--border);
  background: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.65rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition);
  color: var(--text-light);
}

.dot:hover { border-color: var(--gold); background: #fffbea; }
.dot.current { border-color: var(--gold-dark); background: var(--gold); color: var(--black); }
.dot.answered-correct { border-color: var(--green); background: var(--green); color: #fff; }
.dot.answered-wrong { border-color: var(--red); background: var(--red); color: #fff; }
.dot.answered-pending { border-color: #aaa; background: #eee; color: #888; }

/* ===== RESULTS SCREEN ===== */
#results-screen {
  display: none;
  flex-direction: column;
  gap: 20px;
}

.result-hero {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  padding: 36px 32px;
  text-align: center;
}

.result-icon {
  font-size: 4rem;
  margin-bottom: 12px;
  display: block;
}

.result-verdict {
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: 8px;
}

.result-verdict.pass { color: var(--green); }
.result-verdict.fail { color: var(--red); }

.result-score-big {
  font-size: 3.5rem;
  font-weight: 900;
  line-height: 1;
  margin: 12px 0;
}

.result-score-big.pass { color: var(--green); }
.result-score-big.fail { color: var(--red); }

.result-subtitle {
  color: var(--text-light);
  font-size: 0.95rem;
  margin-bottom: 16px;
}

.result-bar-wrap {
  max-width: 360px;
  margin: 0 auto;
}

.result-bar {
  background: var(--border);
  border-radius: 10px;
  height: 12px;
  overflow: hidden;
  margin-bottom: 6px;
}

.result-bar-fill {
  height: 100%;
  border-radius: 10px;
  transition: width 0.8s ease;
}

.result-bar-fill.pass { background: linear-gradient(90deg, #43a047, #2e7d32); }
.result-bar-fill.fail { background: linear-gradient(90deg, #e53935, var(--red)); }

.result-threshold {
  font-size: 0.78rem;
  color: var(--text-light);
  text-align: center;
}

/* Result stats grid */
.result-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 14px;
}

.stat-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px 16px;
  text-align: center;
}

.stat-num {
  font-size: 2rem;
  font-weight: 800;
  display: block;
}

.stat-num.correct { color: var(--green); }
.stat-num.wrong { color: var(--red); }
.stat-num.total { color: var(--black); }
.stat-num.skipped { color: #ff9800; }

.stat-label {
  font-size: 0.8rem;
  color: var(--text-light);
  margin-top: 4px;
}

/* Wrong answers review */
.review-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.review-card h3 {
  padding: 18px 24px;
  font-size: 1rem;
  font-weight: 700;
  border-bottom: 2px solid var(--border);
  display: flex;
  align-items: center;
  gap: 8px;
}

.review-item {
  padding: 16px 24px;
  border-bottom: 1px solid var(--border);
  transition: background var(--transition);
}

.review-item:last-child { border-bottom: none; }
.review-item:hover { background: #fafafa; }

.review-q-num {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-light);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.review-q-text {
  font-size: 0.9rem;
  font-weight: 500;
  margin-bottom: 8px;
  line-height: 1.5;
  color: var(--text);
}

.review-answers {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  font-size: 0.82rem;
}

.review-your {
  color: var(--red);
  display: flex;
  align-items: center;
  gap: 4px;
}

.review-correct {
  color: var(--green);
  display: flex;
  align-items: center;
  gap: 4px;
}

.review-explanation {
  margin-top: 8px;
  font-size: 0.82rem;
  color: #555;
  background: #f0f7ff;
  padding: 8px 12px;
  border-radius: 6px;
  border-left: 3px solid #1976d2;
  line-height: 1.5;
}

/* Result actions */
.result-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

/* ===== ANIMATIONS ===== */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes slideIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.animate-in {
  animation: slideIn 0.3s ease forwards;
}

/* ===== LOADING ===== */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: rgba(255,255,255,0.9);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 999;
  gap: 16px;
  font-size: 1rem;
  color: var(--text-light);
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--border);
  border-top-color: var(--gold);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ===== TOAST ===== */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: var(--black);
  color: #fff;
  padding: 10px 20px;
  border-radius: 24px;
  font-size: 0.88rem;
  z-index: 500;
  transition: transform 0.3s ease;
  white-space: nowrap;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
}

/* ===== EMPTY STATE ===== */
.empty-state {
  text-align: center;
  padding: 40px;
  color: var(--text-light);
  font-size: 0.95rem;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 600px) {
  header h1 { font-size: 1rem; }
  .header-subtitle { display: none; }
  .setup-card { padding: 20px 16px; }
  .mode-buttons { grid-template-columns: 1fr; gap: 10px; }
  .mode-btn { padding: 18px 12px; flex-direction: row; text-align: left; }
  .mode-btn .mode-icon { font-size: 1.8rem; }
  .question-header { padding: 14px 16px; }
  .question-text { font-size: 0.92rem; }
  .options-list { padding: 14px 12px; gap: 8px; }
  .option-label { padding: 10px 12px; font-size: 0.87rem; }
  .quiz-actions { gap: 8px; }
  .btn { padding: 9px 14px; font-size: 0.85rem; }
  .result-hero { padding: 24px 16px; }
  .result-score-big { font-size: 2.8rem; }
  .answered-dots { padding: 12px 16px; }
  .explanation-box { margin: 0 12px 16px; }
  .review-item { padding: 14px 16px; }
  main { padding: 16px 12px 48px; }
}

@media (max-width: 360px) {
  .quiz-counter { font-size: 0.78rem; }
  .btn { padding: 8px 11px; font-size: 0.8rem; }
}