/* ============================================================
   Hero
   ============================================================ */
.hero {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  padding: 64px 24px 56px;
  text-align: center;
}

.hero-inner {
  max-width: 680px;
  margin: 0 auto;
}

.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 14px;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.1;
  color: var(--color-text-primary);
  margin-bottom: 20px;
}

.hero-subtitle {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ============================================================
   Page width
   ============================================================
   A row of five cards needs more than base.css's 1200px, so the nav and
   footer widen to match. They share the padding too: base.css puts the 24px
   gutter inside .nav-inner but outside .lectures-grid, so an equal max-width
   alone leaves the edges 24px apart. landing.css loads only on this page,
   so overriding base.css here is safe. */
.nav-inner,
.lectures-grid,
.footer-inner {
  max-width: 1648px;   /* 5 x 300px card + 4 x 24px gap + 2 x 24px gutter */
  margin: 0 auto;
  padding-left: 24px;
  padding-right: 24px;
}

.lectures-section { padding: 48px 0 72px; }
.site-footer      { padding: 16px 0; }

/* base.css pins html/body to 100dvh and gives main a zero flex basis, both
   for the lecture workspace. This page just stacks, so undo both: releasing
   only the height kept the body one screen tall, and on a short window the
   footer sat across the cards. */
html, body {
  height: auto;
  min-height: 100dvh;
}

main { flex: 1 0 auto; }

/* ============================================================
   Lecture grid
   ============================================================ */
.lectures-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 24px;
}

/* ============================================================
   Lecture card
   ============================================================ */
.lecture-card {
  display: flex;
  flex-direction: column;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: box-shadow 0.18s, border-color 0.18s, transform 0.18s;
  cursor: pointer;
}

.lecture-card:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.lecture-card:hover .card-cta {
  color: var(--color-accent);
}

/* Card header — colored strip with lecture number */
.card-header {
  background: var(--color-accent-light);
  padding: 22px 24px 18px;
  border-bottom: 1px solid var(--color-border-light);
}

.card-number {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 500;
  color: var(--color-accent);
  letter-spacing: -0.02em;
}

/* Card body */
.card-body {
  flex: 1;
  padding: 22px 24px 16px;
}

.card-title {
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 8px;
  color: var(--color-text-primary);
}

.card-desc {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  line-height: 1.55;
}

/* Card footer */
.card-footer {
  padding: 14px 24px 18px;
  border-top: 1px solid var(--color-border-light);
}

.card-cta {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color 0.15s;
}

/* ============================================================
   Responsive
   ============================================================ */
/* Five in a row is held as long as the cards stay readable: below 1200px the
   gaps shrink first, which keeps five columns down to a 1000px window. Below
   that whole columns drop, and the max-width shrinks with them so fewer cards
   don't stretch across 1648px. */
@media (max-width: 1200px) {
  .lectures-grid { gap: 16px; }
}

/* Each step narrows the nav and footer along with the grid, so the three
   boxes keep sharing an edge instead of the cards sliding inward. */
@media (max-width: 1000px) {
  .nav-inner,
  .lectures-grid,
  .footer-inner { max-width: 1056px; }   /* 3 x 320 + 2 x 24 + 2 x 24 */

  .lectures-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  .nav-inner,
  .lectures-grid,
  .footer-inner { max-width: 712px; }    /* 2 x 320 + 24 + 2 x 24 */

  .lectures-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 600px) {
  .hero { padding: 40px 16px 36px; }
  .lectures-section { padding: 32px 0 48px; }

  .nav-inner,
  .lectures-grid,
  .footer-inner {
    max-width: none;
    padding-left: 16px;
    padding-right: 16px;
  }

  .lectures-grid {
    grid-template-columns: 1fr;
    gap: 14px;
  }
}