.lecture-hero {
  position: relative;
  overflow: hidden;
  color: var(--white);
  background: radial-gradient(ellipse at 85% 35%, #30365f, transparent 55%), var(--ink);
}

.lecture-hero::before {
  position: absolute;
  inset: 0;
  background-image: linear-gradient(#ffffff08 1px, transparent 1px), linear-gradient(90deg, #ffffff08 1px, transparent 1px);
  background-size: 100px 100px;
  content: "";
  pointer-events: none;
}

.lecture-hero-content { position: relative; padding-block: 170px 65px; }
.lecture-kicker { margin: 0 0 22px; color: var(--blue-light); font-size: .7rem; letter-spacing: .15em; text-transform: uppercase; }
.lecture-hero h1 { margin: 0; font-size: clamp(4.5rem, 9vw, 8rem); font-weight: 600; letter-spacing: -.06em; line-height: 1; }
.lecture-hero-subtitle { margin: 24px 0 0; font-size: 1.05rem; letter-spacing: .12em; }
.lecture-hero-description { margin: 18px 0 28px; color: #d0d2e0; font-size: .88rem; line-height: 1.9; }
.lecture-hero-link { display: inline-flex; align-items: center; gap: 40px; padding-bottom: 8px; border-bottom: 1px solid #ffffff70; font-size: .8rem; text-decoration: none; }
.lecture-hero-link:hover { color: var(--blue-light); }
.lecture-common { padding-block: 52px 60px; border-bottom: 1px solid var(--line); background: #fff; }
.lecture-section-heading { display: flex; align-items: center; gap: 24px; }
.lecture-section-heading .section-index { margin: 0; }
.lecture-section-heading h2 { margin: 0; font-size: 1.35rem; }
.lecture-common-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-top: 24px; }
.lecture-common-card { display: flex; flex-direction: column; align-items: flex-start; gap: 10px; padding: 24px; border: 1px solid var(--line); background: var(--paper); text-decoration: none; }
.lecture-common-card[href]:hover { border-color: var(--blue); background: #eeeff8; }
.lecture-common-label { color: #515a9c; font-size: .66rem; letter-spacing: .14em; text-transform: uppercase; }
.lecture-common-card strong { font-size: 1rem; }
.lecture-common-description { color: var(--muted); font-size: .78rem; }
.lecture-common-card small { margin-top: auto; padding: 3px 9px; color: #555e72; border: 1px solid #cdd0dc; font-size: .68rem; }
.lecture-directory { padding-block: 64px 100px; scroll-margin-top: 115px; }
.lecture-directory-layout { display: grid; grid-template-columns: minmax(200px, .4fr) minmax(0, 1fr); gap: 64px; align-items: start; }
.lecture-directory-heading { position: sticky; top: 125px; }
.lecture-directory-heading h2 { margin: 12px 0 20px; font-size: 1.8rem; }
.lecture-release-note { margin: 0; color: var(--muted); font-size: .83rem; line-height: 2; }
.lecture-session-list { display: grid; gap: 10px; }
.lecture-session { border: 1px solid var(--line); background: var(--white); scroll-margin-top: 115px; }
.lecture-session summary { display: flex; min-height: 80px; padding: 20px 26px; align-items: center; gap: 20px; list-style: none; cursor: pointer; }
.lecture-session summary::-webkit-details-marker { display: none; }
.lecture-session summary:hover { background: #f0f1f9; }
.lecture-session-number { color: #68709a; font-size: .8rem; font-variant-numeric: tabular-nums; }
.lecture-session-title { font-weight: 650; font-size: 1rem; }
.lecture-session-status { margin-left: auto; color: var(--muted); font-size: .68rem; }
.lecture-toggle { position: relative; width: 24px; height: 24px; flex: 0 0 24px; }
.lecture-toggle::before, .lecture-toggle::after { position: absolute; top: 11px; left: 5px; width: 14px; height: 1px; background: var(--ink); content: ""; }
.lecture-toggle::after { transform: rotate(90deg); }
.lecture-session[open] .lecture-toggle::after { transform: rotate(0); }
.lecture-session[open] summary { background: #eeeff8; }
.lecture-materials { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; padding: 20px 26px 26px; }
.lecture-resource { display: flex; min-height: 58px; padding: 14px; align-items: center; justify-content: space-between; gap: 12px; border: 1px solid var(--line); text-decoration: none; font-size: .8rem; }
.lecture-resource[href] { border-color: var(--blue); color: #424b89; background: #f0f1f9; }
.lecture-resource[href]:hover { background: #e5e7f5; }
.lecture-resource small { color: var(--muted); font-size: .65rem; white-space: nowrap; }
.lecture-page a[aria-disabled="true"] { cursor: not-allowed; }
.lecture-page a:focus-visible, .lecture-session summary:focus-visible { outline: 3px solid var(--blue); outline-offset: 4px; }

@media (max-width: 1000px) {
  .lecture-directory-layout { grid-template-columns: minmax(180px, .35fr) minmax(0, 1fr); gap: 30px; }
  .lecture-common-card { padding: 20px; }
  .lecture-materials { grid-template-columns: 1fr; }
}

@media (max-width: 720px) {
  .lecture-hero-content { padding-block: 125px 48px; }
  .lecture-kicker { font-size: .58rem; }
  .lecture-hero-subtitle { font-size: .95rem; }
  .lecture-common { padding-block: 36px; }
  .lecture-section-heading { align-items: flex-start; flex-direction: column; gap: 8px; }
  .lecture-common-grid { grid-template-columns: 1fr; gap: 12px; }
  .lecture-common-card { gap: 8px; }
  .lecture-directory { padding-block: 40px 60px; }
  .lecture-directory-layout { grid-template-columns: 1fr; gap: 28px; }
  .lecture-directory-heading { position: static; }
  .lecture-directory-heading h2 { margin-block: 8px 12px; }
  .lecture-session summary { min-height: 76px; padding: 18px 16px; gap: 12px; }
  .lecture-session-title { font-size: .9rem; }
  .lecture-session-status { font-size: .6rem; }
  .lecture-materials { padding: 16px; }
}