/* Design system layer.
   This file intentionally sits after custom.css and becomes the source of truth
   for layout, components, readability, and responsiveness. */

:root {
  --main-width: min(1240px, 92vw);
  --nav-width: min(1360px, 96vw);
  --ds-radius-sm: 12px;
  --ds-radius-md: 18px;
  --ds-radius-lg: 26px;
  --ds-gap-1: 0.5rem;
  --ds-gap-2: 0.75rem;
  --ds-gap-3: 1rem;
  --ds-gap-4: 1.5rem;
  --ds-gap-5: 2rem;
  --ds-gap-6: 3rem;
  --ds-shadow-soft: 0 12px 32px rgba(53, 38, 22, 0.08);
  --ds-shadow-hover: 0 18px 40px rgba(53, 38, 22, 0.14);
  --ds-page-max: 1420px;
}

:root:not([data-theme="dark"]) {
  --theme: #f5efe5;
  --entry: #fffdf8;
  --primary: #24180f;
  --secondary: #685846;
  --tertiary: #e6d9ca;
  --content: #2b2118;
  --code-bg: #f0e7db;
  --border: rgba(77, 58, 36, 0.14);
  --surface-muted: #efe6da;
  --surface-strong: #e7ddd0;
  --surface-grey: #ebe9e4;
  --accent: #5c3d1e;
  --accent-soft: #7d5b39;
  --accent-2: #245a45;
}

:root[data-theme="dark"] {
  --theme: #151310;
  --entry: #1d1814;
  --primary: #f4eadc;
  --secondary: #ccbda8;
  --tertiary: #3a3128;
  --content: #eadfce;
  --code-bg: #211b17;
  --border: rgba(255, 241, 220, 0.12);
  --surface-muted: #1c1813;
  --surface-strong: #201a15;
  --surface-grey: #1a1917;
  --accent: #e0c29a;
  --accent-soft: #f0d8b7;
  --accent-2: #79cfa8;
  --ds-shadow-soft: 0 16px 42px rgba(0, 0, 0, 0.28);
  --ds-shadow-hover: 0 24px 52px rgba(0, 0, 0, 0.34);
}

html {
  scroll-padding-top: 6.5rem;
}

body {
  color: var(--content);
  background:
    radial-gradient(1200px 700px at 10% -10%, rgba(92, 61, 30, 0.08), transparent 60%),
    radial-gradient(800px 500px at 100% 0%, rgba(36, 90, 69, 0.07), transparent 55%),
    var(--theme);
}

.main {
  max-width: var(--main-width);
  padding: clamp(1rem, 2vw, 1.5rem);
}

.header {
  position: sticky;
  top: 0;
  z-index: 80;
  border-bottom: 1px solid var(--border);
  background: color-mix(in oklab, var(--theme) 92%, var(--surface-grey));
  backdrop-filter: blur(14px) saturate(150%);
}

.nav {
  gap: var(--ds-gap-3);
}

#menu {
  gap: 1.1rem;
}

#menu a span {
  padding-bottom: 0.18rem;
  border-bottom: 2px solid transparent;
}

#menu a .active,
#menu a:hover span {
  border-bottom-color: var(--accent);
}

a {
  color: inherit;
}

.page-shell {
  max-width: var(--ds-page-max);
  margin: 0 auto;
}

.home-shell {
  padding-top: 0.75rem;
}

.home-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 320px);
  gap: clamp(1.25rem, 2vw, 2rem);
  align-items: start;
}

.home-main {
  min-width: 0;
}

.home-sidebar {
  position: sticky;
  top: 5.6rem;
  align-self: start;
  display: grid;
  gap: 1rem;
}

.home-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(240px, 0.8fr);
  gap: clamp(1rem, 2vw, 2rem);
  padding: clamp(1.5rem, 3vw, 2.5rem);
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-lg);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.18), rgba(255, 255, 255, 0)),
    linear-gradient(135deg, color-mix(in oklab, var(--surface-muted) 88%, white), color-mix(in oklab, var(--entry) 86%, transparent));
  box-shadow: var(--ds-shadow-soft);
  align-items: center;
}

.home-hero-title {
  margin: 0 0 0.85rem;
  font-size: clamp(2.3rem, 5.6vw, 4.4rem);
  line-height: 0.96;
  color: var(--primary);
}

a.home-hero-title-link {
  color: inherit;
  text-decoration: none;
  border-radius: 0.08em;
}

a.home-hero-title-link:hover {
  color: var(--accent);
}

a.home-hero-title-link:focus-visible {
  outline: 2px solid var(--accent-2);
  outline-offset: 3px;
}

.home-hero-description {
  max-width: 58ch;
  margin: 0;
  font-size: clamp(1.02rem, 1.45vw, 1.22rem);
  line-height: 1.62;
  color: var(--secondary);
}

.home-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.35rem;
}

.home-hero-equation {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 180px;
  padding: 1rem;
  border: 1px dashed var(--border);
  border-radius: var(--ds-radius-md);
  background: color-mix(in oklab, var(--entry) 78%, transparent);
  color: var(--primary);
}

.home-hero-equation .katex-display {
  margin: 0;
}

/* Homepage: primary course hero (replaces generic tagline + equation) */
.home-hero--course {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  padding: 0;
  overflow: hidden;
}

.home-hero--course-inner {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.home-hero-course-row {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(220px, 0.8fr);
  gap: clamp(1rem, 2vw, 2rem);
  padding: clamp(1.5rem, 3vw, 2.5rem);
  align-items: start;
}

.home-hero-course-visual {
  border-radius: var(--ds-radius-md);
  overflow: hidden;
  border: 1px solid var(--border);
  background: color-mix(in oklab, var(--entry) 90%, var(--theme));
  align-self: stretch;
  display: flex;
  align-items: center;
  justify-content: center;
}

.home-hero-course-img {
  display: block;
  width: 100%;
  height: auto;
  max-height: min(420px, 52vh);
  object-fit: cover;
  vertical-align: middle;
}

.home-hero-course-img--empty {
  min-height: 200px;
  width: 100%;
  background: linear-gradient(145deg, color-mix(in oklab, var(--surface-muted) 70%, var(--entry)), var(--entry));
}

.page-hero,
.section-block,
.surface-card,
.sidebar-panel,
.box {
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  background: var(--entry);
  box-shadow: var(--ds-shadow-soft);
}

.page-hero {
  margin-bottom: 1.25rem;
  padding: clamp(1.35rem, 2vw, 2rem);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0)),
    var(--surface-muted);
}

.page-hero--article {
  margin-bottom: 1rem;
}

.page-hero-inner {
  max-width: 78ch;
}

.page-eyebrow,
.section-label,
.eyebrow,
.eyebrow-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  margin: 0 0 0.5rem;
  color: var(--accent-2);
  font-size: 0.77rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.eyebrow-badge {
  padding: 0.25rem 0.5rem;
  border-radius: 999px;
  background: color-mix(in oklab, var(--accent) 12%, var(--entry));
  color: var(--accent);
}

.page-title,
.section-title {
  margin: 0;
  color: var(--primary);
  line-height: 1.02;
}

.page-title {
  font-size: clamp(2rem, 4vw, 3.2rem);
}

.section-title {
  font-size: clamp(1.5rem, 2vw, 2.15rem);
}

.page-description,
.section-description {
  margin-top: 0.75rem;
  color: var(--secondary);
  max-width: 68ch;
  line-height: 1.62;
  font-size: 1rem;
}

.section-block {
  margin-top: 1.25rem;
  padding: 1.35rem;
}

.section-block--feature {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0)),
    var(--surface-strong);
}

.section-block--muted {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), rgba(255, 255, 255, 0)),
    var(--surface-grey);
}

.section-block--prose {
  padding: 1.4rem 1.5rem;
}

.section-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  padding-bottom: 1rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid color-mix(in oklab, var(--border) 100%, transparent);
}

.section-head--compact {
  padding-bottom: 0.75rem;
  margin-bottom: 0.9rem;
}

.prose-block {
  max-width: 72ch;
}

.article-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

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

.article-card {
  min-width: 0;
}

.article-card-link {
  display: block;
  height: 100%;
  color: inherit;
  text-decoration: none;
}

.article-card-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  height: 100%;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.14), rgba(255, 255, 255, 0)),
    var(--entry);
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.article-card-link:hover .article-card-shell,
.pillar-card:hover,
.term-card:hover,
.dm-carousel-card:hover,
.article-paginav-link:hover {
  transform: translateY(-2px);
  box-shadow: var(--ds-shadow-hover);
  border-color: color-mix(in oklab, var(--accent) 28%, var(--border));
}

.article-card--feature .article-card-shell {
  grid-template-columns: minmax(280px, 0.9fr) minmax(0, 1.1fr);
  min-height: 320px;
}

.article-card-media {
  aspect-ratio: 16 / 10;
  background:
    linear-gradient(135deg, color-mix(in oklab, var(--surface-strong) 92%, transparent), color-mix(in oklab, var(--surface-muted) 88%, transparent));
  overflow: hidden;
}

.article-card--feature .article-card-media {
  aspect-ratio: auto;
  min-height: 100%;
}

.article-card-media img,
.article-lead-media img,
.pm-figure img,
.dm-carousel-media img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
}

.article-card-media--placeholder,
.dm-carousel-media--placeholder {
  position: relative;
}

.article-card-media--placeholder::before,
.dm-carousel-media--placeholder::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 20% 25%, rgba(92, 61, 30, 0.18), transparent 40%),
    radial-gradient(circle at 80% 70%, rgba(36, 90, 69, 0.18), transparent 36%);
}

.article-card-body {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  padding: 1rem 1.1rem 1.1rem;
}

.article-card-title,
.dm-carousel-title,
.pillar-title,
.term-card-title,
.article-paginav-title {
  margin: 0;
  color: var(--primary);
  line-height: 1.12;
}

.article-card-title {
  font-size: 1.35rem;
  overflow-wrap: anywhere;
}

.article-card--feature .article-card-title {
  font-size: clamp(1.75rem, 2.5vw, 2.4rem);
}

.article-card-summary,
.dm-carousel-desc,
.pillar-description,
.term-card-count,
.article-card-meta,
.meta,
.profile-bio,
.recent-list a,
.tag-pill {
  color: var(--secondary);
}

.article-card-summary,
.dm-carousel-desc,
.pillar-description {
  margin: 0;
  line-height: 1.58;
}

.article-card-summary {
  display: -webkit-box;
  overflow: hidden;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 4;
}

.article-card-footer {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 0.75rem;
  flex-wrap: wrap;
  margin-top: auto;
}

.article-card-meta {
  margin: 0;
  font-size: 0.94rem;
}

.article-card-cta {
  color: var(--accent);
  font-weight: 700;
}

.pillar-grid,
.terms-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.pillar-card,
.term-card {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  min-height: 180px;
  padding: 1rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  text-decoration: none;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.14), rgba(255, 255, 255, 0)),
    color-mix(in oklab, var(--entry) 92%, var(--surface-muted));
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.term-card-count {
  margin-top: auto;
}

.dm-subnav-wrap {
  position: sticky;
  top: 4.8rem;
  z-index: 30;
  margin-top: 1rem;
}

.dm-subnav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  padding: 0.6rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: color-mix(in oklab, var(--entry) 90%, var(--surface-muted));
  box-shadow: var(--ds-shadow-soft);
}

.dm-subnav-link {
  padding: 0.4rem 0.8rem;
  border-radius: 999px;
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--secondary);
  border: 1px solid transparent;
}

.dm-subnav-link:hover,
.dm-subnav-link.is-active {
  color: var(--primary);
  background: color-mix(in oklab, var(--entry) 70%, var(--surface-grey));
  border-color: var(--border);
}

.dm-carousel {
  outline: none;
}

.dm-carousel-track {
  display: flex;
  gap: 1rem;
  overflow-x: auto;
  padding-bottom: 0.2rem;
  scroll-snap-type: x mandatory;
  scrollbar-width: thin;
  -webkit-overflow-scrolling: touch;
}

.dm-carousel-slide {
  flex: 0 0 min(420px, 82vw);
  scroll-snap-align: start;
}

.dm-carousel-card {
  display: grid;
  grid-template-columns: 128px 1fr;
  overflow: hidden;
  min-height: 180px;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  background: var(--entry);
  text-decoration: none;
  color: inherit;
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.dm-carousel-media {
  background: color-mix(in oklab, var(--surface-muted) 84%, transparent);
}

.dm-carousel-body {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  padding: 0.9rem 1rem;
}

.dm-carousel-tools {
  display: flex;
  gap: 0.4rem;
}

.dm-carousel-btn {
  width: 2.4rem;
  height: 2.4rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--entry);
  color: var(--primary);
  cursor: pointer;
}

.sidebar-panel {
  padding: 1rem 1.05rem;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  background: var(--entry);
  box-shadow: var(--ds-shadow-soft);
}

.profile-card > .section-label {
  margin-bottom: 0.35rem;
}

.profile-name {
  margin: 0 0 0.4rem;
  font-size: 1.55rem;
  color: var(--primary);
}

.profile-bio > :first-child {
  margin-top: 0;
}

.profile-bio > :last-child {
  margin-bottom: 0;
}

.sidebar-social {
  margin-top: 1rem;
  padding-top: 0.9rem;
  border-top: 1px dashed var(--border);
}

.sidebar-social .social-icons {
  justify-content: flex-start;
  gap: 0.65rem;
}

.sidebar-links {
  display: grid;
  gap: 0.55rem;
}

.sidebar-links a {
  text-decoration: none;
  font-weight: 600;
  color: var(--primary);
}

.search-shell {
  max-width: 1180px;
}

.section-block--search {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0)),
    var(--surface-grey);
}

.search-toolbar {
  display: grid;
  grid-template-columns: minmax(0, 1.8fr) repeat(2, minmax(180px, 0.7fr));
  gap: 0.9rem;
  margin-bottom: 1rem;
}

.search-field,
.search-filter {
  display: grid;
  gap: 0.35rem;
}

.search-field input,
.search-filter select {
  width: 100%;
  padding: 0.82rem 0.95rem;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-sm);
  background: var(--entry);
  color: var(--primary);
  font: inherit;
}

.search-field input:focus,
.search-filter select:focus {
  outline: 2px solid color-mix(in oklab, var(--accent) 28%, transparent);
  outline-offset: 1px;
}

.search-status {
  margin-bottom: 1rem;
  color: var(--secondary);
  font-size: 0.95rem;
}

.search-results {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.search-result-card .article-card-shell {
  min-height: 100%;
}

.series-panel {
  padding: 1rem 1.1rem;
}

.series-list {
  display: grid;
  gap: 0.65rem;
}

.series-link {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: baseline;
  padding: 0.8rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-sm);
  background: color-mix(in oklab, var(--entry) 82%, var(--surface-muted));
  text-decoration: none;
}

.series-link-title {
  color: var(--primary);
  font-weight: 600;
}

.series-link-meta {
  color: var(--secondary);
  font-size: 0.9rem;
  white-space: nowrap;
}

.recent-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.55rem;
}

.recent-list li {
  margin: 0;
}

.recent-list a {
  text-decoration: none;
}

.tags-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag-pill {
  display: inline-flex;
  align-items: center;
  padding: 0.38rem 0.75rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: color-mix(in oklab, var(--entry) 76%, var(--surface-muted));
  text-decoration: none;
  font-size: 0.92rem;
}

.article-shell {
  max-width: 1100px;
}

.article-layout {
  display: grid;
}

.article-main {
  display: grid;
  gap: 1rem;
}

.article-toolbar,
.article-meta,
.article-toc,
.comments-box {
  padding: 1rem 1.1rem;
}

.post-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  color: var(--secondary);
  font-size: 0.94rem;
}

.article-lead-media {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  box-shadow: var(--ds-shadow-soft);
  aspect-ratio: 16 / 7;
}

.article-content {
  padding: clamp(1.25rem, 2vw, 2rem);
}

.post-content,
.prose-block {
  font-size: 1.08rem;
  line-height: 1.75;
}

.post-content > :first-child,
.prose-block > :first-child {
  margin-top: 0;
}

.post-content h2,
.post-content h3,
.post-content h4 {
  line-height: 1.12;
  margin-top: 1.8rem;
  color: var(--primary);
}

/* Course: Markdown / page headings in green (accent-2) */
.article-shell--course .page-title,
.article-shell--course .post-content h1,
.article-shell--course .post-content h2,
.article-shell--course .post-content h3,
.article-shell--course .post-content h4,
.article-shell--course .post-content h5,
.article-shell--course .post-content h6 {
  color: var(--accent-2);
}

.article-shell--course {
  max-width: 1160px;
}

.article-shell--course .page-title {
  max-width: 32ch;
  font-size: clamp(1.85rem, 3vw, 2.85rem);
  line-height: 1.08;
}

.page-shell--course .article-grid--three {
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 320px), 1fr));
}

.page-shell--course .article-card--compact .article-card-media {
  aspect-ratio: 16 / 9;
  max-height: 240px;
}

.page-shell--course .page-title,
.page-shell--course .section-title,
.page-shell--course .prose-block h1,
.page-shell--course .prose-block h2,
.page-shell--course .prose-block h3,
.page-shell--course .prose-block h4,
.page-shell--course .prose-block h5,
.page-shell--course .prose-block h6 {
  color: var(--accent-2);
}

.post-content .katex-display {
  margin: 1.2rem 0;
  padding: 1rem 0.9rem;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-sm);
  background: color-mix(in oklab, var(--entry) 82%, var(--surface-muted));
  overflow-x: auto;
}

.post-tags {
  list-style: none;
  padding: 0;
  margin: 0 0 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.post-tags a {
  display: inline-flex;
  align-items: center;
  padding: 0.38rem 0.75rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  text-decoration: none;
  color: var(--secondary);
  background: color-mix(in oklab, var(--entry) 76%, var(--surface-muted));
}

.article-footer {
  display: grid;
  gap: 1rem;
}

.article-paginav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.article-paginav-link {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 1rem 1.1rem;
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  text-decoration: none;
  background: var(--entry);
  transition: transform 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.article-paginav-label {
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent-2);
}

.article-paginav-title {
  font-size: 1.08rem;
}

.breadcrumbs {
  margin-bottom: 0.65rem;
  color: var(--secondary);
  font-size: 0.92rem;
}

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

.pagination {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.pagination a {
  display: inline-flex;
  align-items: center;
  padding: 0.7rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: var(--entry);
  color: var(--primary);
  text-decoration: none;
}

.empty-state {
  grid-column: 1 / -1;
  margin: 0;
  padding: 1rem 1.1rem;
  border: 1px dashed var(--border);
  border-radius: var(--ds-radius-sm);
  color: var(--secondary);
  background: color-mix(in oklab, var(--entry) 88%, var(--surface-grey));
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  padding: 0.75rem 1.1rem;
  border-radius: 999px;
  border: 1px solid transparent;
  text-decoration: none;
  font-weight: 700;
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease, background 0.15s ease;
}

.button:hover {
  transform: translateY(-1px);
}

.button-primary {
  background: var(--accent);
  color: #fffdf8;
  box-shadow: 0 10px 24px rgba(92, 61, 30, 0.2);
}

.button-secondary,
.button-ghost {
  background: color-mix(in oklab, var(--entry) 78%, var(--surface-muted));
  border-color: var(--border);
  color: var(--primary);
}

.nav-tree {
  margin: 0;
  padding: 0;
  background: transparent;
  border: 0;
  box-shadow: none;
}

.nav-tree-content {
  border-top-color: var(--border);
}

.tree-section h4 {
  color: var(--primary);
}

.tree-link {
  background: color-mix(in oklab, var(--entry) 76%, var(--surface-muted));
  color: var(--secondary);
  border: 1px solid var(--border);
}

.tree-link:hover {
  background: var(--accent);
  color: #fffdf8;
}

.tree-count {
  background: color-mix(in oklab, var(--entry) 90%, var(--surface-grey));
}

.pm-figure,
.pm-video,
.pm-embed,
.callout {
  margin: 1.35rem 0;
}

.pm-figure img,
.pm-video-frame,
.pm-embed {
  border: 1px solid var(--border);
  border-radius: var(--ds-radius-md);
  box-shadow: var(--ds-shadow-soft);
}

.pm-video-frame {
  overflow: hidden;
}

.pm-embed {
  overflow: hidden;
  aspect-ratio: 16 / 9;
  background: #000;
}

.pm-embed iframe,
.responsive-video {
  width: 100%;
  height: 100%;
  display: block;
  border: 0;
}

.figure-caption,
.video-caption {
  margin-top: 0.55rem;
  text-align: center;
  color: var(--secondary);
  font-size: 0.94rem;
}

.callout {
  padding: 1rem 1.1rem;
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: var(--ds-radius-sm);
  background: color-mix(in oklab, var(--entry) 74%, var(--surface-muted));
}

.callout-tip {
  border-left-color: var(--accent-2);
}

.callout-warning {
  border-left-color: #b86c2d;
}

.callout-title {
  margin-bottom: 0.4rem;
  font-weight: 700;
  color: var(--primary);
}

.callout-body > :first-child {
  margin-top: 0;
}

.callout-body > :last-child {
  margin-bottom: 0;
}

#home-hero,
#latest-feature,
#spotlights,
#most-read,
#essential,
#featured-research,
#pillars,
#collections,
#latest,
#site-profile {
  scroll-margin-top: 6.5rem;
}

@media (max-width: 1100px) {
  .article-grid--three,
  .pillar-grid,
  .terms-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .home-sidebar {
    position: static;
  }
}

@media (max-width: 860px) {
  .home-hero,
  .home-hero-course-row,
  .article-card--feature .article-card-shell,
  .dm-carousel-card {
    grid-template-columns: 1fr;
  }

  .home-hero-equation {
    min-height: 140px;
  }

  .article-grid,
  .article-grid--three,
  .pillar-grid,
  .terms-grid,
  .article-paginav,
  .search-results,
  .search-toolbar {
    grid-template-columns: 1fr;
  }

  .section-block,
  .page-hero,
  .article-content {
    padding: 1rem;
  }

  .dm-subnav-wrap {
    top: 4.2rem;
  }

  .series-link {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 560px) {
  .main {
    padding: 0.85rem;
  }

  .home-hero {
    padding: 1rem;
  }

  .page-title {
    font-size: 1.8rem;
  }

  .section-title {
    font-size: 1.4rem;
  }

  .button {
    width: 100%;
  }

  .home-hero-actions {
    flex-direction: column;
  }
}