:root {
  --bg: #f6f3ef;
  --surface: #ffffff;
  --ink: #1f2a32;
  --muted: #5f6e78;
  --accent: #c28b5c;
  --accent-soft: #e7d2c1;
  --border: #e2ded8;
  --shadow-soft: 0 18px 40px rgba(31, 42, 50, 0.12);
  --shadow-hover: 0 22px 50px rgba(31, 42, 50, 0.18);
  --radius-lg: 18px;
  --radius-md: 14px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  color: var(--ink);
  font-family: "IBM Plex Serif", "PT Serif", Georgia, serif;
  line-height: 1.6;
  background-color: var(--bg);
  background-image:
    radial-gradient(circle at 12% 12%, rgba(194, 139, 92, 0.12), transparent 45%),
    radial-gradient(circle at 80% 10%, rgba(126, 167, 166, 0.18), transparent 40%),
    radial-gradient(circle at 20% 80%, rgba(226, 222, 216, 0.8), transparent 55%);
  min-height: 100vh;
}

a {
  color: inherit;
  text-decoration: none;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.page {
  max-width: 1100px;
  margin: 0 auto;
  padding: 32px 24px 40px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-mark {
  width: 38px;
  height: 38px;
  border-radius: 12px;
  background: linear-gradient(140deg, #f6e6d9 0%, #f0caa8 55%, #c28b5c 100%);
  box-shadow: 0 10px 20px rgba(194, 139, 92, 0.3);
}

.brand-title {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 0.82rem;
}

.brand-sub {
  font-size: 0.92rem;
  color: var(--muted);
}

.pill {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.85rem;
  padding: 6px 14px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  box-shadow: 0 8px 20px rgba(31, 42, 50, 0.08);
}

.hero {
  max-width: 720px;
}

.eyebrow {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.7rem;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 12px;
}

h1 {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: clamp(2rem, 1.2rem + 2.6vw, 3.2rem);
  margin: 0 0 16px;
}

.lead {
  margin: 0;
  font-size: 1.05rem;
  color: var(--muted);
}

.grid {
  --grid-gap: 18px;
  display: grid;
  gap: var(--grid-gap);
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
}

.topic-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 20px 20px 22px;
  background: var(--surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-soft);
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
  animation: rise 0.6s ease both;
  animation-delay: var(--delay, 0ms);
}

.topic-card h3 {
  margin: 0;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 1.1rem;
}

.topic-card p {
  margin: 0;
  color: var(--muted);
}

.topic-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: var(--shadow-hover);
}

.card-link {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.9rem;
  color: var(--accent);
}

.section-hero {
  max-width: 720px;
}

.notice-card {
  margin-top: 20px;
  background: var(--surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  padding: 18px 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  box-shadow: var(--shadow-soft);
}

.notice-card p {
  margin: 0;
  font-size: 1rem;
  color: var(--muted);
}

.back-link {
  align-self: flex-start;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.95rem;
  background: var(--ink);
  color: #fff;
  padding: 10px 18px;
  border-radius: 999px;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 10px 18px rgba(31, 42, 50, 0.18);
}

.back-link:hover {
  transform: translateY(-2px);
}

.ghost-link {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.9rem;
  color: var(--muted);
  padding: 6px 10px;
  border-radius: 8px;
  border: 1px solid transparent;
  transition: border-color 0.2s ease, color 0.2s ease;
}

.ghost-link:hover {
  color: var(--ink);
  border-color: var(--border);
}

.site-footer {
  margin-top: auto;
  font-size: 0.85rem;
  color: var(--muted);
}

.study {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.section-hero--study {
  max-width: 860px;
}

.section-title {
  margin: 0;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: clamp(1.4rem, 1rem + 1.2vw, 2rem);
}

.section-lead {
  margin: 0;
  color: var(--muted);
}

.study-section {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.study-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.study-card {
  background: var(--surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  padding: 18px 20px;
  box-shadow: var(--shadow-soft);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.study-card--soft {
  background: #fbf7f2;
}

.study-card--accent {
  border-left: 4px solid var(--accent);
}

.study-card h3,
.study-card h4 {
  margin: 0;
  font-family: "Manrope", "PT Sans", sans-serif;
}

.study-card p,
.study-card ul,
.study-card ol {
  margin: 0;
}

.card-kicker {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.7rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

.card-split {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.card-list {
  margin: 0;
  padding-left: 18px;
}

.card-list--tight {
  padding-left: 16px;
}

.card-list li {
  margin-bottom: 8px;
}

.card-list li:last-child {
  margin-bottom: 0;
}

.note {
  color: var(--muted);
  font-size: 0.95rem;
}

.chip-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.chip {
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border);
  font-size: 0.82rem;
  color: var(--muted);
}

.definition-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.definition-card {
  background: var(--surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  padding: 16px 18px;
  box-shadow: var(--shadow-soft);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.definition-term {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-weight: 700;
}

.definition-simple {
  background: var(--accent-soft);
  border-radius: 12px;
  padding: 10px 12px;
  font-size: 0.95rem;
}

.feature-card {
  background: var(--surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  padding: 16px 18px;
  box-shadow: var(--shadow-soft);
}

.feature-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 10px;
}

.feature-item {
  padding: 10px 12px;
  border-radius: 12px;
  background: #fdf9f5;
  border: 1px dashed var(--accent-soft);
}

.feature-item strong {
  display: block;
  font-family: "Manrope", "PT Sans", sans-serif;
}

.timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.timeline li {
  padding-left: 14px;
  border-left: 3px solid var(--accent-soft);
}

.details-card {
  border-top: 1px dashed var(--border);
  padding-top: 12px;
}

details summary {
  cursor: pointer;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-weight: 600;
}

details summary::-webkit-details-marker {
  display: none;
}

details[open] summary {
  margin-bottom: 12px;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}


.video-layout {
  display: grid;
  gap: 18px;
  grid-template-columns: minmax(0, 1.5fr) minmax(280px, 0.9fr);
  align-items: start;
}

.video-player-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.video-frame {
  position: relative;
  overflow: hidden;
  border-radius: 16px;
  border: 1px solid var(--border);
  background: #111;
  box-shadow: var(--shadow-soft);
  aspect-ratio: 16 / 9;
}

.video-frame iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

.video-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 14px;
}

.video-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border-radius: 999px;
  background: var(--ink);
  color: #fff;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.92rem;
  box-shadow: 0 10px 18px rgba(31, 42, 50, 0.18);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.video-link:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.video-meta {
  color: var(--muted);
  font-size: 0.95rem;
}

.video-aside {
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 16px 18px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background: linear-gradient(180deg, #fffdf9 0%, #f8f2eb 100%);
  box-shadow: var(--shadow-soft);
}

.video-aside-head {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.video-aside-head h4,
.video-aside-head p {
  margin: 0;
}

.video-aside-head p {
  color: var(--muted);
  font-size: 0.95rem;
}

.timestamp-list {
  display: grid;
  gap: 10px;
}

.timestamp-btn {
  width: 100%;
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.88);
  border-radius: 14px;
  padding: 10px 12px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  text-align: left;
  color: var(--ink);
  font: inherit;
  cursor: pointer;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease, background-color 0.2s ease;
}

.timestamp-btn span:first-child {
  flex: 0 0 auto;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.82rem;
  color: var(--accent);
  font-weight: 700;
}

.timestamp-btn span:last-child {
  flex: 1 1 auto;
}

.timestamp-btn:hover {
  transform: translateY(-1px);
  border-color: var(--accent);
  box-shadow: 0 10px 22px rgba(31, 42, 50, 0.08);
  background: #fff;
}

.timestamp-btn.is-active {
  border-color: var(--accent);
  background: #fff;
  box-shadow: 0 12px 24px rgba(194, 139, 92, 0.16);
}

@media (prefers-reduced-motion: reduce) {
  .topic-card {
    animation: none;
  }

  .topic-card:hover,
  .back-link:hover {
    transform: none;
  }
}

@media (min-width: 1024px) {
  .topic-card--center {
    grid-column: 2 / span 2;
    justify-self: center;
    width: calc((100% - var(--grid-gap)) / 2);
  }
}

@media (max-width: 900px) {
  .video-layout {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .page {
    padding: 24px 18px 32px;
  }

  .site-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .pill {
    align-self: flex-start;
  }

  .timestamp-btn {
    align-items: flex-start;
    flex-direction: column;
  }
}


.video-placeholder {
  min-height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 14px;
  padding: 24px;
  border-radius: 18px;
  border: 1px solid var(--border);
  background:
    radial-gradient(circle at top left, rgba(194, 139, 92, 0.18), transparent 42%),
    linear-gradient(180deg, #1f2a32 0%, #2d3b45 100%);
  color: #fff;
  box-shadow: var(--shadow-soft);
  aspect-ratio: 16 / 9;
}

.video-placeholder h4,
.video-placeholder p {
  margin: 0;
}

.video-placeholder h4 {
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: clamp(1.25rem, 1rem + 1vw, 1.7rem);
}

.video-placeholder p {
  max-width: 56ch;
  color: rgba(255, 255, 255, 0.84);
}

.video-placeholder-mark {
  align-self: flex-start;
  padding: 6px 12px;
  border-radius: 999px;
  font-family: "Manrope", "PT Sans", sans-serif;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #fff;
  background: rgba(255, 255, 255, 0.14);
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.video-placeholder .chip {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.16);
  color: rgba(255, 255, 255, 0.86);
}

.placeholder-list {
  display: grid;
  gap: 10px;
}

.placeholder-item {
  display: grid;
  grid-template-columns: 40px 1fr;
  gap: 12px;
  align-items: start;
  padding: 12px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.88);
}

.placeholder-item span:first-child {
  font-family: "Manrope", "PT Sans", sans-serif;
  color: var(--accent);
  font-weight: 700;
}