/* ── Learn AI page ── */

/* Hero */
.learn-hero {
  text-align: center;
  padding: 3rem 0 2rem;
}

.learn-hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  font-weight: 900;
  line-height: 1.1;
  margin: 0.75rem 0 1rem;
}

.learn-hero h1 span {
  background: linear-gradient(135deg, var(--accent), var(--accent-3));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.learn-hero .lead {
  max-width: 56ch;
  margin: 0 auto 1.5rem;
}

.learn-hero-cta {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

.learn-meta {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  font-size: 0.82rem;
  color: var(--muted);
}

.learn-meta .dot {
  opacity: 0.4;
}

/* Table of contents */
.learn-toc {
  display: flex;
  gap: 0.25rem 1rem;
  flex-wrap: wrap;
  align-items: center;
  padding: 1.25rem 0;
  margin: 1.5rem 0 2rem;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.learn-toc-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-right: 0.5rem;
}

.learn-toc a {
  font-size: 0.82rem;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 0.2rem 0;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.learn-toc a:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* Sections */
.learn-section {
  padding: 2.5rem 0;
}

.learn-section h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800;
  margin: 0 0 0.25rem;
}

.learn-subtitle {
  color: var(--muted);
  margin: 0 0 2rem;
  max-width: 64ch;
  font-size: 1rem;
  line-height: 1.7;
}

/* Card grid (AI/ML/DL) */
.learn-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1rem;
}

.learn-card {
  padding: 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.learn-card:hover {
  border-color: var(--border-bright);
  transform: translateY(-2px);
}

.learn-card-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
}

.learn-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin: 0 0 0.5rem;
}

.learn-card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}

/* Flow diagram */
.learn-flow {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 0;
  flex-wrap: wrap;
  padding: 2rem 1rem;
  border-radius: var(--radius-lg);
  background: var(--surface);
  border: 1px solid var(--border);
  margin-bottom: 1.5rem;
}

.learn-flow-step {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.4rem;
  min-width: 120px;
  max-width: 160px;
  padding: 0.75rem;
}

.learn-flow-num {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  font-family: var(--mono);
  color: var(--muted);
}

.learn-flow-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.learn-flow-step strong {
  font-size: 0.85rem;
  font-weight: 700;
}

.learn-flow-step span {
  font-size: 0.75rem;
  color: var(--muted);
  line-height: 1.4;
}

.learn-flow-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2.5rem 0.25rem 0;
  color: var(--muted);
  opacity: 0.5;
}

/* Callout */
.learn-callout {
  display: flex;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  border-radius: var(--radius);
  border: 1px solid rgba(99, 102, 241, 0.2);
  background: rgba(99, 102, 241, 0.05);
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.learn-callout-icon {
  flex-shrink: 0;
  margin-top: 0.1rem;
  color: var(--accent);
}

.learn-callout strong {
  color: var(--text);
}

/* Accordion */
.learn-accordion {
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
}

.learn-accordion-item {
  border-bottom: 1px solid var(--border);
}

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

.learn-accordion-trigger {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  width: 100%;
  padding: 1rem 1.25rem;
  border: none;
  background: var(--surface);
  color: var(--text);
  font: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  text-align: left;
  transition: background 0.15s ease;
}

.learn-accordion-trigger:hover {
  background: var(--surface-hover);
}

.learn-accordion-trigger svg:first-child {
  flex-shrink: 0;
  color: var(--accent-2);
}

.learn-accordion-trigger span {
  flex: 1;
}

.learn-chevron {
  flex-shrink: 0;
  transition: transform 0.2s ease;
  color: var(--muted);
}

.learn-accordion-trigger[aria-expanded="true"] .learn-chevron {
  transform: rotate(180deg);
}

.learn-accordion-content {
  padding: 0 1.25rem 1rem;
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  display: none;
}

.learn-accordion-trigger[aria-expanded="true"] + .learn-accordion-content {
  display: block;
}

.learn-accordion-content p {
  margin: 0 0 0.5rem;
}

.learn-accordion-content a {
  color: var(--accent-2);
  text-decoration: none;
}

.learn-accordion-content a:hover {
  text-decoration: underline;
}

/* Inference diagram */
.learn-diagram {
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  background: var(--surface);
  border: 1px solid var(--border);
  margin-bottom: 1.5rem;
  overflow-x: auto;
}

.learn-diagram-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-width: max-content;
}

.learn-diagram-box {
  padding: 0.75rem 1rem;
  border-radius: var(--radius);
  border: 1px solid;
  background: rgba(0,0,0,0.2);
  min-width: 110px;
  text-align: center;
}

.learn-diagram-label {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.25rem;
  opacity: 0.7;
}

.learn-diagram-value {
  font-size: 0.78rem;
  font-weight: 500;
}

.learn-diagram-arrow {
  font-size: 1.2rem;
  color: var(--muted);
  flex-shrink: 0;
}

/* Stats row */
.learn-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0.75rem;
}

.learn-stat {
  padding: 1rem 0.75rem;
  border-radius: var(--radius);
  background: var(--surface);
  border: 1px solid var(--border);
  text-align: center;
}

.learn-stat strong {
  display: block;
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--accent-2);
  margin-bottom: 0.2rem;
}

.learn-stat span {
  font-size: 0.78rem;
  color: var(--muted);
}

/* Comparison */
.learn-comparison {
  display: flex;
  align-items: stretch;
  gap: 1rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.learn-comp-card {
  flex: 1;
  min-width: 200px;
  padding: 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface);
}

.learn-comp-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin: 0 0 1rem;
}

.learn-comp-card ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.learn-comp-card li {
  padding: 0.35rem 0;
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.learn-comp-card li::before {
  content: "✗ ";
  color: var(--danger);
  font-weight: 700;
}

.learn-comp-card--win li::before {
  content: "✓ ";
  color: var(--success);
}

.learn-comp-divider {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: 0 0.25rem;
}

/* Table */
.learn-table-wrap {
  overflow-x: auto;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin-bottom: 1.5rem;
}

.learn-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.learn-table th {
  text-align: left;
  padding: 0.75rem 1rem;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.learn-table th:first-child {
  width: 26%;
}

.learn-table td {
  padding: 0.7rem 1rem;
  border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
  line-height: 1.5;
}

.learn-table td:first-child {
  color: var(--text);
  font-weight: 600;
}

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

.learn-table tbody tr:hover {
  background: rgba(255, 255, 255, 0.015);
}

/* Resources grid */
.learn-resources {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}

.learn-resource-card {
  padding: 1.25rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--surface);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.learn-resource-card:hover {
  border-color: var(--border-bright);
  transform: translateY(-2px);
}

.learn-resource-tag {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  background: rgba(99, 102, 241, 0.1);
  color: var(--accent);
  margin-bottom: 0.75rem;
}

.learn-resource-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin: 0 0 0.4rem;
}

.learn-resource-card p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin: 0 0 0.75rem;
}

.learn-resource-link {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent-2);
  text-decoration: none;
}

.learn-resource-link:hover {
  text-decoration: underline;
}

/* CTA */
.learn-cta {
  text-align: center;
  padding: 3rem 0;
  border-top: 1px solid var(--border);
  margin-top: 2rem;
}

.learn-cta h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800;
  margin: 0 0 0.5rem;
}

.learn-cta p {
  color: var(--muted);
  margin: 0 0 1.5rem;
}

.learn-cta-btns {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* Responsive */
@media (max-width: 640px) {
  .learn-flow {
    flex-direction: column;
    align-items: center;
  }

  .learn-flow-arrow {
    transform: rotate(90deg);
    padding: 0.25rem 0;
  }

  .learn-comp-divider {
    flex-direction: row;
    width: 100%;
  }

  .learn-diagram-row {
    flex-direction: column;
  }

  .learn-diagram-arrow {
    transform: rotate(90deg);
  }
}

/* ── Infographic SVG ── */
.learn-infographic {
  display: block;
  width: 100%;
  max-width: 720px;
  height: auto;
  margin: 1.5rem auto;
  border-radius: var(--radius);
}

/* ── Timeline ── */
.learn-timeline {
  position: relative;
  padding: 1rem 0 0.5rem 2rem;
  margin-bottom: 1.5rem;
}

.learn-timeline::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 10px;
  width: 2px;
  background: var(--border);
}

.learn-timeline-item {
  position: relative;
  padding: 0 0 2rem 1.5rem;
}

.learn-timeline-item:last-child {
  padding-bottom: 0;
}

.learn-timeline-marker {
  position: absolute;
  left: -1.85rem;
  top: 0.3rem;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--bg);
  z-index: 1;
}

.learn-timeline-marker--alt {
  background: var(--accent-2);
}

.learn-timeline-marker--alt2 {
  background: var(--accent-3);
}

.learn-timeline-era {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-2);
  margin-bottom: 0.15rem;
}

.learn-timeline-item h3 {
  font-size: 1rem;
  font-weight: 700;
  margin: 0 0 0.35rem;
}

.learn-timeline-item p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin: 0 0 0.35rem;
}

.learn-timeline-item ul {
  margin: 0.35rem 0 0;
  padding: 0;
  list-style: none;
}

.learn-timeline-item li {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.6;
  padding: 0.1rem 0;
}

.learn-timeline-item li::before {
  content: "• ";
  color: var(--accent);
  font-weight: 700;
}

/* ── Analogy callout ── */
.learn-analogy {
  display: flex;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  margin-bottom: 1.5rem;
  border-radius: var(--radius);
  border: 1px solid rgba(245, 158, 11, 0.2);
  background: rgba(245, 158, 11, 0.05);
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.learn-analogy-icon {
  flex-shrink: 0;
  margin-top: 0.1rem;
  color: var(--accent-4);
}

.learn-analogy strong {
  color: var(--text);
}

/* ── Use case icons ── */
.learn-card-icon--sm {
  width: 38px;
  height: 38px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 0.75rem;
}

/* ── Future accordion extras ── */
.learn-future-meta {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 0.5rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent-2);
}

/* Responsive extras */
@media (max-width: 640px) {
  .learn-timeline {
    padding-left: 1.25rem;
  }

  .learn-timeline-marker {
    left: -1.4rem;
    width: 12px;
    height: 12px;
  }
}