/* ==========================================================================
   AIGround — Course & Lesson Styles (course.css)
   Light, editorial. Loaded on course landing + lesson pages, with style.css.
   Relies on tokens defined in style.css :root.
   ========================================================================== */

/* --------------------------------------------------------------------------
   SECTION 1 — Lesson page structure
   -------------------------------------------------------------------------- */
.lesson-header-bar {
  background: var(--color-surface-alt);
  border-bottom: 1px solid var(--color-border);
  padding-block: 14px;
}

.lesson-breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  font-size: 0.82rem;
  color: var(--color-text-muted);
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: clamp(16px, 4vw, 32px);
}

.lesson-breadcrumb a {
  color: var(--color-text-muted);
  text-decoration: none;
  transition: color var(--transition);
}

.lesson-breadcrumb a:hover {
  color: var(--color-accent);
}

.lesson-breadcrumb .sep {
  color: var(--color-border-strong);
}

.lesson-hero {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding-block: 40px 36px;
}

.lesson-hero .container {
  max-width: var(--max-width);
}

.lesson-hero-tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.lesson-hero-title {
  font-size: clamp(2.4rem, 5vw, 3.8rem);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--color-text-primary);
  margin-bottom: 12px;
  max-width: 760px;
}

.lesson-hero-intro {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 640px;
  line-height: 1.7;
  margin-bottom: 20px;
}

.lesson-hero-meta {
  display: flex;
  align-items: center;
  gap: 20px;
  flex-wrap: wrap;
  font-size: 0.82rem;
  color: var(--color-text-muted);
  padding-top: 16px;
  border-top: 1px solid var(--color-border);
}

.lesson-hero-meta span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* --------------------------------------------------------------------------
   SECTION 2 — Two-column grid
   -------------------------------------------------------------------------- */
.lesson-wrapper {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 48px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding-inline: clamp(16px, 4vw, 32px);
  padding-block: 48px;
  align-items: start;
}

.lesson-main {
  min-width: 0;
}

/* --------------------------------------------------------------------------
   SECTION 3 — Lesson body content
   -------------------------------------------------------------------------- */
.lesson-body h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-block: 44px 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-border);
  scroll-margin-top: 88px;
  letter-spacing: -0.01em;
}

.lesson-body h2::before {
  content: none;
}

.lesson-body h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-block: 32px 12px;
  scroll-margin-top: 88px;
}

.lesson-body p {
  font-size: 1rem;
  line-height: 1.85;
  color: var(--color-text-secondary);
  margin-bottom: 20px;
  max-width: none;
}

.lesson-body strong {
  color: var(--color-text-primary);
  font-weight: 700;
}

.lesson-body a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.lesson-body ul,
.lesson-body ol {
  list-style: none;
  padding: 0;
  margin-bottom: 24px;
}

.lesson-body ul li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 10px;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
}

.lesson-body ul li::before {
  content: "\2013";
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: 700;
}

.lesson-body ol {
  counter-reset: lesson-ol;
}

.lesson-body ol li {
  counter-increment: lesson-ol;
  position: relative;
  padding-left: 32px;
  margin-bottom: 12px;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
}

.lesson-body ol li::before {
  content: counter(lesson-ol);
  position: absolute;
  left: 0;
  top: 2px;
  width: 20px;
  height: 20px;
  background: var(--color-accent);
  color: #fff;
  border-radius: 50%;
  font-size: 0.7rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.lesson-body blockquote {
  margin-block: 28px;
  padding: 16px 22px;
  background: var(--color-surface-alt);
  border-left: 3px solid var(--color-accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--color-text-secondary);
  font-style: italic;
}

.lesson-body blockquote p {
  margin: 0;
  max-width: none;
  color: var(--color-text-secondary);
}

/* --------------------------------------------------------------------------
   SECTION 4 — Content breakers
   -------------------------------------------------------------------------- */
.callout-box {
  display: flex;
  gap: 16px;
  border-radius: var(--radius-lg);
  padding: 20px 24px;
  margin-block: 32px;
}

.callout-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.callout-content {
  flex: 1;
}

.callout-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: 4px;
}

.callout-body {
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--color-text-secondary);
  margin: 0;
  max-width: none;
}

.callout--tip {
  background: rgba(34, 197, 94, 0.06);
  border: 1px solid rgba(34, 197, 94, 0.2);
}

.callout--warning {
  background: rgba(217, 119, 6, 0.06);
  border: 1px solid rgba(217, 119, 6, 0.2);
}

.callout--info {
  background: var(--color-accent-light);
  border: 1px solid rgba(45, 125, 111, 0.2);
}

.step-block-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin-block: 28px;
}

.step-block {
  display: flex;
  gap: 20px;
  padding: 20px 24px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 0;
  border-bottom: none;
}

.step-block:first-child {
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}

.step-block:last-child {
  border-bottom: 1px solid var(--color-border);
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

.step-number {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  background: var(--color-accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 800;
  margin-top: 2px;
}

.step-content h4 {
  font-weight: 700;
  margin-bottom: 6px;
  color: var(--color-text-primary);
}

.step-content p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin: 0;
  max-width: none;
}

.code-block {
  position: relative;
  background: #1E2030;
  border-radius: var(--radius-lg);
  padding: 20px 24px;
  margin-block: 28px;
  font-family: 'Courier New', Courier, monospace;
  font-size: 0.875rem;
  line-height: 1.7;
  color: #CDD6F4;
  overflow-x: auto;
}

.code-block .copy-btn {
  position: absolute;
  top: 12px;
  right: 12px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-sm);
  padding: 4px 10px;
  font-size: 0.7rem;
  color: rgba(255, 255, 255, 0.6);
  cursor: pointer;
  font-family: var(--font-base);
  transition: all var(--transition);
}

.code-block .copy-btn:hover {
  background: rgba(255, 255, 255, 0.2);
  color: #fff;
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  margin-block: 28px;
  font-size: 0.9rem;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.comparison-table th {
  background: var(--color-surface-alt);
  padding: 12px 16px;
  text-align: left;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  font-weight: 700;
  border-bottom: 1px solid var(--color-border);
}

.comparison-table td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-secondary);
}

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

.comparison-table tr:hover td {
  background: var(--color-accent-light);
}

.key-takeaway {
  margin-block: 48px 32px;
  padding: 28px 32px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-top: 3px solid var(--color-accent);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
}

.key-takeaway::before {
  content: "Key Takeaway";
  display: block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-accent);
  margin-bottom: 10px;
}

.key-takeaway p {
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--color-text-primary);
  font-weight: 500;
  margin: 0;
  max-width: none;
}

.divider-label {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-block: 40px;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
}

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

.image-block {
  margin-block: 32px;
}

.image-block img {
  width: 100%;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.image-block figcaption {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  text-align: center;
  margin-top: 10px;
  font-style: italic;
}

/* --------------------------------------------------------------------------
   SECTION 5 — Sticky sidebar
   -------------------------------------------------------------------------- */
.lesson-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + 24px);
  height: fit-content;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.toc-box {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.toc-header {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  margin-bottom: 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.toc-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.toc-list a {
  display: block;
  font-size: 0.84rem;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding: 5px 8px;
  border-radius: var(--radius-sm);
  border-left: 2px solid transparent;
  transition: all 0.15s ease;
}

.toc-list a:hover {
  color: var(--color-accent);
  background: var(--color-accent-light);
  border-left-color: var(--color-accent);
}

.toc-list a.active {
  color: var(--color-accent);
  font-weight: 600;
  background: var(--color-accent-light);
  border-left-color: var(--color-accent);
}

.toc-list .toc-h3 a {
  padding-left: 18px;
  font-size: 0.8rem;
}

.course-progress-box {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow-sm);
}

.progress-header {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  margin-bottom: 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
}

.progress-lessons {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 1px;
}

.progress-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 7px 8px;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: background 0.15s ease;
}

.progress-item:hover {
  background: var(--color-surface-alt);
}

.progress-item.active {
  color: var(--color-accent);
  background: var(--color-accent-light);
  font-weight: 600;
}

.progress-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  flex-shrink: 0;
  background: var(--color-border);
}

.progress-item.active .progress-dot {
  background: var(--color-accent);
}

.progress-item.completed .progress-dot {
  background: var(--color-success);
}

.sidebar-cta {
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 20px;
  text-align: center;
}

.sidebar-cta .pill-badge {
  margin-bottom: 10px;
}

.sidebar-cta p {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: 14px;
  max-width: none;
  line-height: 1.5;
}

.sidebar-cta .btn-primary {
  width: 100%;
  justify-content: center;
  font-size: 0.85rem;
  padding: 9px 16px;
}

/* --------------------------------------------------------------------------
   SECTION 6 — Prev/next nav
   -------------------------------------------------------------------------- */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  align-items: stretch;
  gap: 16px;
  max-width: var(--max-width);
  margin-inline: auto;
  padding: clamp(32px, 5vw, 48px) clamp(16px, 4vw, 32px);
  border-top: 1px solid var(--color-border);
}

.lesson-nav-btn {
  display: flex;
  align-items: center;
  gap: 14px;
  flex: 1;
  max-width: 48%;
  padding: 18px 22px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  text-decoration: none;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
}

.lesson-nav-btn:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.lesson-nav-btn--next {
  justify-content: flex-end;
  text-align: right;
  margin-left: auto;
}

.nav-btn-label {
  display: block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  margin-bottom: 4px;
}

.nav-btn-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text-primary);
  line-height: 1.3;
}

.nav-btn-arrow {
  font-size: 1.3rem;
  color: var(--color-accent);
  flex-shrink: 0;
}

/* --------------------------------------------------------------------------
   SECTION 7 — Course landing page
   -------------------------------------------------------------------------- */
.course-page-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding-block: 56px 48px;
}

.course-hero-grid {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 48px;
  align-items: start;
  max-width: var(--max-width);
  margin-inline: auto;
  padding-inline: clamp(16px, 4vw, 32px);
}

.course-hero-right {
  position: sticky;
  top: calc(var(--nav-height) + 24px);
}

.course-info-card {
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.course-info-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

.course-info-item:last-child {
  border-bottom: none;
}

.course-info-item .info-icon {
  font-size: 1.1rem;
  width: 24px;
  text-align: center;
  flex-shrink: 0;
}

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

.lesson-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.lesson-list-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  text-decoration: none;
  transition: all 0.15s ease;
}

.lesson-list-item:last-child {
  border-bottom: none;
}

.lesson-list-item:hover {
  background: var(--color-accent-light);
}

.lesson-list-item.locked {
  opacity: 0.5;
  pointer-events: none;
}

.lesson-number-badge {
  width: 30px;
  height: 30px;
  flex-shrink: 0;
  background: var(--color-accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.72rem;
  font-weight: 800;
}

.lesson-list-item.locked .lesson-number-badge {
  background: var(--color-border);
}

.lesson-item-content {
  flex: 1;
  min-width: 0;
}

.lesson-item-title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-primary);
}

.lesson-item-meta {
  font-size: 0.78rem;
  color: var(--color-text-muted);
  margin-top: 2px;
}

/* --------------------------------------------------------------------------
   SECTION 8 — FAQ accordion
   -------------------------------------------------------------------------- */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.faq-item {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}

.faq-item:last-child {
  border-bottom: none;
}

.faq-item.open {
  background: var(--color-accent-light);
}

.faq-question {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 18px 24px;
  background: transparent;
  border: none;
  cursor: pointer;
  text-align: left;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-primary);
  font-family: var(--font-base);
  transition: color var(--transition);
}

.faq-question:hover {
  color: var(--color-accent);
}

.faq-icon {
  width: 22px;
  height: 22px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  transition: transform var(--transition), background var(--transition);
}

.faq-item.open .faq-icon {
  transform: rotate(45deg);
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #fff;
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.faq-item.open .faq-answer {
  max-height: 400px;
}

.faq-answer-inner {
  padding: 4px 24px 20px;
  font-size: 0.9rem;
  line-height: 1.75;
  color: var(--color-text-secondary);
}

/* --------------------------------------------------------------------------
   SECTION 9 — Mobile course (≤768px)
   -------------------------------------------------------------------------- */
@media (max-width: 768px) {
  .lesson-wrapper {
    grid-template-columns: 1fr;
    gap: 32px;
    padding-block: 32px;
  }

  .lesson-sidebar {
    position: static;
  }

  .toc-box {
    display: none;
  }

  .lesson-hero-title {
    font-size: clamp(1.8rem, 5vw, 2.4rem);
  }

  .lesson-nav {
    flex-direction: column;
    gap: 12px;
  }

  .lesson-nav-btn {
    max-width: 100%;
  }

  .lesson-nav-btn--next {
    text-align: left;
    justify-content: flex-start;
    margin-left: 0;
  }

  .course-hero-grid {
    grid-template-columns: 1fr;
  }

  .course-hero-right {
    position: static;
  }

  /* Course info card items wrap on mobile */
  .course-info-item {
    flex-wrap: wrap;
  }

  /* Lesson list items readable on mobile */
  .lesson-list-item {
    padding: 12px 14px;
  }

  .lesson-item-title {
    font-size: 0.9rem;
  }

  /* Key takeaway readable on mobile */
  .key-takeaway {
    padding: 20px;
  }

  /* Comparison table — horizontal scroll on mobile */
  .comparison-table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  /* Code blocks — horizontal scroll on mobile */
  .code-block {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    font-size: 0.8rem;
  }

  /* Step blocks — tighter on mobile */
  .step-block {
    grid-template-columns: 36px 1fr;
    gap: 12px;
    padding: 16px;
  }
}