:root {
  --color-bg: #f5f7fa;
  --color-surface: #ffffff;
  --color-text: #1c2530;
  --color-muted: #5c6b7a;
  --color-border: #e1e6eb;
  --color-primary: #1a56db;
  --color-primary-dark: #12409e;
  --color-success: #1a7f37;
  --color-success-bg: #e7f6ec;
  --color-danger: #c0292f;
  --color-danger-bg: #fbeaea;
  --color-warning-bg: #fff6e0;
  --color-warning-text: #7a5a00;
  --radius: 10px;
  --max-width: 1080px;
  font-size: 16px;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

body {
  font-family: "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, Helvetica, Arial, sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.55;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* Header */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 10;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 0.85rem;
  padding-bottom: 0.85rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--color-text);
}

.brand:hover {
  text-decoration: none;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--color-primary), #4f8ef7);
  color: white;
  font-weight: 800;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.main-nav {
  display: flex;
  gap: 1.25rem;
  font-weight: 600;
  font-size: 0.95rem;
}

.btn-ads-toggle {
  padding: 0.4rem 0.75rem;
  font-size: 0.8rem;
  white-space: nowrap;
}

/* Ad slots */
.ad-slot {
  background: var(--color-surface);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius);
  color: var(--color-muted);
  font-size: 0.8rem;
  text-align: center;
  padding: 0.75rem;
  margin: 1.5rem auto;
  max-width: var(--max-width);
}

.ad-slot--header {
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-slot--inline {
  min-height: 90px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.ad-slot--sidebar {
  min-height: 250px;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Hero */
.hero {
  padding: 2.5rem 0 1.5rem;
  text-align: center;
}

.hero h1 {
  font-size: 2.2rem;
  margin-bottom: 0.5rem;
}

.hero p {
  color: var(--color-muted);
  max-width: 640px;
  margin: 0 auto;
}

/* Module grid */
.section-title {
  font-size: 1.3rem;
  margin: 2rem 0 1rem;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.module-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.module-card h3 {
  margin: 0;
  font-size: 1.05rem;
}

.module-level {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-primary);
  font-weight: 700;
}

.module-desc {
  color: var(--color-muted);
  font-size: 0.9rem;
  flex-grow: 1;
}

.badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  width: fit-content;
}

.badge--soon {
  background: var(--color-warning-bg);
  color: var(--color-warning-text);
}

.badge--available {
  background: var(--color-success-bg);
  color: var(--color-success);
}

.module-progress {
  font-size: 0.8rem;
  color: var(--color-muted);
}

.module-actions {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.55rem 1rem;
  border-radius: 8px;
  border: 1px solid transparent;
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  background: var(--color-primary);
  color: white;
}

.btn:hover {
  background: var(--color-primary-dark);
  text-decoration: none;
}

.btn.btn-secondary {
  background: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.btn.btn-secondary:hover {
  background: rgba(26, 86, 219, 0.08);
}

.btn:disabled,
.btn.disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

.btn-block {
  width: 100%;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--color-border);
  margin-top: 3rem;
  padding: 1.75rem 0;
  color: var(--color-muted);
  font-size: 0.85rem;
}

.disclaimer {
  background: var(--color-warning-bg);
  color: var(--color-warning-text);
  border-radius: var(--radius);
  padding: 0.85rem 1rem;
  font-size: 0.85rem;
  margin: 1.5rem 0;
}

/* Module detail page */
.module-header {
  padding: 2rem 0 1rem;
}

.module-header h1 {
  margin-bottom: 0.25rem;
}

.mode-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
  margin: 1.5rem 0;
}

.mode-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
}

.mode-card h3 {
  margin-top: 0;
}

.mode-card ul {
  padding-left: 1.1rem;
  color: var(--color-muted);
  font-size: 0.9rem;
}

.history-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--color-surface);
  border-radius: var(--radius);
  overflow: hidden;
  font-size: 0.9rem;
}

.history-table th,
.history-table td {
  padding: 0.6rem 0.8rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.history-table tr:last-child td {
  border-bottom: none;
}

.pass-pill {
  color: var(--color-success);
  font-weight: 700;
}

.fail-pill {
  color: var(--color-danger);
  font-weight: 700;
}

/* Quiz runner */
.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 0;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.quiz-progress {
  font-weight: 600;
}

.quiz-timer {
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
}

.quiz-timer.low-time {
  background: var(--color-danger-bg);
  color: var(--color-danger);
  border-color: var(--color-danger);
}

.progress-bar {
  height: 6px;
  background: var(--color-border);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 1rem;
}

.progress-bar-fill {
  height: 100%;
  background: var(--color-primary);
  transition: width 0.2s ease;
}

.question-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
}

.question-meta {
  font-size: 0.78rem;
  color: var(--color-muted);
  margin-bottom: 0.5rem;
}

.question-text {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 1rem;
}

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

.option {
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 0.7rem 0.9rem;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  transition: border-color 0.15s ease, background 0.15s ease;
}

.option:hover {
  border-color: var(--color-primary);
}

.option input {
  margin-top: 0.2rem;
}

.option.selected {
  border-color: var(--color-primary);
  background: rgba(26, 86, 219, 0.06);
}

.option.correct {
  border-color: var(--color-success);
  background: var(--color-success-bg);
}

.option.incorrect {
  border-color: var(--color-danger);
  background: var(--color-danger-bg);
}

.feedback-box {
  margin-top: 1rem;
  padding: 0.85rem 1rem;
  border-radius: 8px;
  font-size: 0.9rem;
}

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

.feedback-box.incorrect {
  background: var(--color-danger-bg);
  color: var(--color-danger);
}

.quiz-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 1.5rem 0 2.5rem;
}

/* Results page */
.score-summary {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: center;
  margin: 1.5rem 0;
}

.score-value {
  font-size: 3rem;
  font-weight: 800;
}

.score-value.pass {
  color: var(--color-success);
}

.score-value.fail {
  color: var(--color-danger);
}

.result-status {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.review-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.25rem;
  margin-bottom: 1rem;
}

.review-item .question-text {
  margin-bottom: 0.6rem;
}

.review-answer-line {
  font-size: 0.88rem;
  margin: 0.15rem 0;
}

.filter-bar {
  display: flex;
  gap: 0.5rem;
  margin: 1rem 0;
  flex-wrap: wrap;
}

.filter-bar .btn {
  padding: 0.4rem 0.8rem;
  font-size: 0.82rem;
}

.empty-state {
  text-align: center;
  color: var(--color-muted);
  padding: 2rem;
}

@media (max-width: 640px) {
  .hero h1 {
    font-size: 1.6rem;
  }
  .quiz-nav {
    flex-direction: column;
  }
}