:root {
  color-scheme: light;
  --bg: #f8fafc;
  --surface: rgba(255, 255, 255, 0.76);
  --ink: #101418;
  --muted: #64707d;
  --quiet: #8a95a3;
  --line: #dce3ea;
  --line-strong: #c9d4de;
  --accent: #0f766e;
  --accent-2: #7c3aed;
  --accent-soft: rgba(15, 118, 110, 0.12);
  --shadow: 0 22px 80px rgba(16, 20, 24, 0.08);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #050607;
  --surface: rgba(13, 16, 19, 0.72);
  --ink: #f5f7fa;
  --muted: #a0a9b5;
  --quiet: #767f8b;
  --line: #1e262d;
  --line-strong: #2d3842;
  --accent: #2dd4bf;
  --accent-2: #a78bfa;
  --accent-soft: rgba(45, 212, 191, 0.12);
  --shadow: 0 26px 100px rgba(0, 0, 0, 0.34);
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(180deg, color-mix(in srgb, var(--accent-soft) 70%, transparent), transparent 460px),
    var(--bg);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  letter-spacing: 0;
  text-rendering: optimizeLegibility;
}

a,
button,
input {
  color: inherit;
  font: inherit;
}

a {
  text-decoration: none;
}

button {
  border: 0;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  gap: 24px;
  padding: 28px clamp(20px, 5vw, 56px);
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: blur(18px);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 70%, transparent);
}

.site-name {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 780;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  transition: color 160ms ease;
}

.site-name:hover {
  color: var(--ink);
}

.site-nav {
  display: flex;
  justify-self: center;
  gap: 18px;
  color: var(--quiet);
  font-size: 0.7rem;
  font-weight: 780;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.site-nav a {
  padding: 4px 0 5px;
  border-bottom: 1px solid transparent;
  transition:
    border-color 160ms ease,
    color 160ms ease;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--ink);
  border-bottom-color: var(--accent);
}

.theme-toggle {
  display: grid;
  justify-self: end;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 999px;
  background: transparent;
  cursor: pointer;
  opacity: 0.78;
  transition:
    background 160ms ease,
    opacity 160ms ease;
}

.theme-toggle:hover {
  background: color-mix(in srgb, var(--ink) 8%, transparent);
  opacity: 1;
}

.theme-icon {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 2;
}

.theme-icon-sun,
:root[data-theme="dark"] .theme-icon-moon {
  display: none;
}

:root[data-theme="dark"] .theme-icon-sun {
  display: block;
}

.page-main {
  width: min(100% - 40px, 1080px);
  margin: 0 auto;
  padding: 72px 0 96px;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(190px, 270px);
  align-items: end;
  gap: clamp(36px, 8vw, 112px);
  min-height: 420px;
}

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

.eyebrow {
  margin: 0 0 22px;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 780;
  letter-spacing: 0.24em;
  text-transform: uppercase;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  max-width: 760px;
  margin-bottom: 20px;
  font-size: clamp(3.2rem, 11vw, 7.7rem);
  font-weight: 260;
  letter-spacing: 0;
  line-height: 0.9;
}

.hero-copy > p:not(.eyebrow) {
  max-width: 590px;
  margin-bottom: 30px;
  color: var(--muted);
  font-size: clamp(1.03rem, 1.4vw, 1.2rem);
  line-height: 1.7;
}

.source-link {
  display: inline-flex;
  align-items: center;
  min-height: 38px;
  border-bottom: 1px solid var(--accent);
  color: var(--ink);
  font-size: 0.74rem;
  font-weight: 780;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  transition:
    color 160ms ease,
    border-color 160ms ease;
}

.source-link:hover {
  color: var(--accent);
  border-bottom-color: var(--accent-2);
}

.source-preview {
  margin: 0;
  justify-self: end;
  color: var(--quiet);
}

.source-preview img {
  display: block;
  width: min(100%, 246px);
  height: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
  opacity: 0.92;
}

.source-preview figcaption {
  margin-top: 12px;
  color: var(--quiet);
  font-size: 0.72rem;
  font-weight: 720;
  letter-spacing: 0.16em;
  text-align: center;
  text-transform: uppercase;
}

.search-panel {
  position: sticky;
  top: 91px;
  z-index: 5;
  margin: 54px 0 70px;
  padding: 20px 0;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(18px);
  border-block: 1px solid color-mix(in srgb, var(--line) 80%, transparent);
}

.search-panel label {
  display: block;
  margin-bottom: 11px;
  color: var(--quiet);
  font-size: 0.72rem;
  font-weight: 780;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.search-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 18px;
}

.search-row input {
  width: 100%;
  min-height: 54px;
  border: 0;
  border-bottom: 1px solid var(--line-strong);
  color: var(--ink);
  background: transparent;
  font-size: clamp(1.5rem, 3vw, 2.35rem);
  font-weight: 280;
  outline: none;
}

.search-row input::placeholder {
  color: color-mix(in srgb, var(--muted) 58%, transparent);
}

.search-row input:focus {
  border-bottom-color: var(--accent);
}

.search-row output {
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 780;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  white-space: nowrap;
}

.syllabus {
  display: grid;
  gap: 72px;
}

.topic-block {
  display: grid;
  grid-template-columns: minmax(180px, 250px) minmax(0, 1fr);
  gap: clamp(24px, 5vw, 64px);
  padding-top: 28px;
  border-top: 1px solid var(--line);
}

.block-header {
  position: sticky;
  top: 194px;
  align-self: start;
}

.block-header p {
  margin-bottom: 11px;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 780;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}

.block-header h2 {
  margin-bottom: 0;
  color: var(--ink);
  font-size: clamp(1.35rem, 2vw, 2rem);
  font-weight: 320;
  line-height: 1.1;
}

.topic-list {
  display: grid;
  gap: 0;
  margin: 0;
  padding: 0;
  list-style: none;
}

.topic-item {
  border-bottom: 1px solid var(--line);
}

.topic-row {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 18px;
  min-height: 68px;
  align-items: center;
  padding: 16px 0;
  color: var(--muted);
  line-height: 1.45;
  transition: color 160ms ease;
}

.topic-number {
  color: var(--quiet);
  font-size: 0.75rem;
  font-weight: 780;
  letter-spacing: 0.12em;
  transition: color 160ms ease;
}

.topic-item:hover .topic-row {
  color: var(--ink);
}

.topic-item:hover .topic-number {
  color: var(--accent);
}

.empty-state {
  margin: 64px 0 0;
  color: var(--muted);
  text-align: center;
}

.site-footer {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  padding: 0 24px 44px;
  color: var(--quiet);
  font-size: 0.72rem;
  font-weight: 780;
  letter-spacing: 0.22em;
  text-transform: uppercase;
}

.site-footer a {
  transition: color 160ms ease;
}

.site-footer a:hover {
  color: var(--accent);
}

.site-footer span {
  width: 4px;
  height: 4px;
  border-radius: 999px;
  background: currentColor;
  opacity: 0.7;
}

:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 44%, transparent);
  outline-offset: 5px;
}

@media (max-width: 820px) {
  .site-header {
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 14px 16px;
    padding: 22px 24px;
  }

  .site-nav {
    grid-column: 1 / -1;
    grid-row: 2;
    justify-self: center;
    gap: 16px;
    font-size: 0.64rem;
    letter-spacing: 0.12em;
  }

  .page-main {
    width: min(100% - 32px, 1080px);
    padding-top: 52px;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: 0;
  }

  .source-preview {
    display: none;
  }

  .search-panel {
    top: 107px;
    margin: 44px 0 52px;
  }

  .search-row {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .search-row output {
    justify-self: start;
  }

  .topic-block {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .block-header {
    position: static;
  }

  .topic-row {
    grid-template-columns: 36px minmax(0, 1fr);
    gap: 14px;
    min-height: 64px;
  }

  .site-footer {
    flex-wrap: wrap;
    gap: 16px;
    padding-bottom: 32px;
    font-size: 0.66rem;
    letter-spacing: 0.16em;
  }
}

@media (max-width: 460px) {
  .page-main {
    width: min(100% - 28px, 1080px);
  }

  h1 {
    font-size: clamp(3rem, 16vw, 4.6rem);
  }

  .search-row input {
    font-size: 1.45rem;
  }

  .topic-row {
    grid-template-columns: 1fr;
    gap: 8px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
  }
}