/* rhino-bird-2026 · Site styles
 * Layer 3+: layout chrome, sidebar nav, content area, responsive
 */

/* ── Topbar ── */
.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  gap: var(--jx-space-4);
  height: var(--rb-topbar-h);
  padding: 0 var(--jx-gutter);
  background: var(--jx-surface);
  border-bottom: 1px solid var(--jx-rule);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}
.topbar .site-title {
  font-family: var(--jx-font-display);
  font-size: var(--jx-fs-lg);
  font-weight: var(--jx-weight-heading);
  color: var(--jx-ink);
  text-decoration: none;
  white-space: nowrap;
  letter-spacing: var(--jx-tracking-h3);
}
.topbar .site-title:hover { color: var(--jx-accent); }
.topbar .jx-return-to-hub { margin-left: auto; }

/* ── Topbar search ── */
.topbar-search {
  position: relative;
  flex: 1 1 12rem;
  max-width: 22rem;
  margin-left: var(--jx-space-2);
}
.topbar-search__input {
  width: 100%;
  height: 2rem;
  padding: 0 var(--jx-space-3);
  border: 1px solid var(--jx-rule);
  border-radius: var(--jx-radius-pill);
  background: var(--jx-paper);
  color: var(--jx-ink);
  font-family: var(--jx-font-ui);
  font-size: var(--jx-fs-sm);
  transition: border-color var(--jx-duration-fast) var(--jx-easing),
              box-shadow var(--jx-duration-fast) var(--jx-easing);
}
.topbar-search__input::placeholder { color: var(--jx-ink-muted); }
.topbar-search__input:focus {
  outline: none;
  border-color: var(--jx-accent);
  box-shadow: 0 0 0 2px var(--jx-accent-tint);
}
.topbar-search__results {
  position: absolute;
  top: calc(100% + var(--jx-space-2));
  left: 0;
  right: 0;
  z-index: 200;
  max-height: 20rem;
  overflow-y: auto;
  background: var(--jx-surface);
  border: 1px solid var(--jx-rule);
  border-radius: var(--jx-radius-3);
  box-shadow: var(--jx-shadow-md, 0 8px 24px rgba(0, 0, 0, 0.12));
}
.topbar-search__item {
  display: block;
  padding: var(--jx-space-3) var(--jx-space-4);
  color: var(--jx-ink);
  text-decoration: none;
  border-bottom: 1px solid var(--jx-rule);
}
.topbar-search__item:last-child { border-bottom: none; }
.topbar-search__item:hover,
.topbar-search__item.is-active {
  background: var(--jx-accent-tint);
}
.topbar-search__item-title {
  display: block;
  font-size: var(--jx-fs-sm);
  font-weight: var(--jx-weight-ui);
  line-height: 1.35;
}
.topbar-search__item-excerpt {
  display: block;
  margin-top: var(--jx-space-1);
  font-size: var(--jx-fs-xs);
  color: var(--jx-ink-muted);
  line-height: 1.4;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.topbar-search__empty {
  padding: var(--jx-space-4);
  font-size: var(--jx-fs-sm);
  color: var(--jx-ink-muted);
  text-align: center;
}
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ── Mobile menu toggle ── */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 20px;
  cursor: pointer;
  color: var(--jx-ink-2);
  padding: var(--jx-space-2);
}

/* ── Shell: sidebar + content ── */
.shell {
  display: grid;
  grid-template-columns: var(--rb-sidebar-w) 1fr;
  min-height: calc(100vh - var(--rb-topbar-h));
}

/* ── Sidebar ── */
.sidebar {
  position: sticky;
  top: var(--rb-topbar-h);
  height: calc(100vh - var(--rb-topbar-h));
  overflow-y: auto;
  padding: var(--jx-space-5) var(--jx-space-4);
  border-right: 1px solid var(--jx-rule);
  background: var(--jx-paper);
  font-size: var(--jx-fs-sm);
}
.sidebar::-webkit-scrollbar { width: 3px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--jx-rule); border-radius: var(--jx-radius-pill); }

.nav-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.nav-list li { margin: 0; }
.nav-list a {
  display: block;
  padding: var(--jx-space-2) var(--jx-space-3);
  color: var(--jx-ink-2);
  text-decoration: none;
  border-radius: var(--jx-radius-2);
  transition: background var(--jx-duration-fast) var(--jx-easing),
              color var(--jx-duration-fast) var(--jx-easing);
  line-height: 1.4;
}
.nav-list a:hover {
  background: var(--jx-accent-tint);
  color: var(--jx-accent);
}
.nav-list a.active {
  background: var(--jx-accent-tint);
  color: var(--jx-accent);
  font-weight: var(--jx-weight-ui);
}

/* Nested nav (children) */
.nav-list .nav-children {
  list-style: none;
  padding-left: var(--jx-space-4);
  margin: 0;
}
.nav-list .nav-children a {
  font-size: var(--jx-fs-xs);
  padding: var(--jx-space-1) var(--jx-space-3);
}

/* Category label in sidebar (non-interactive divider) */
.nav-category {
  font-family: var(--jx-font-mono);
  font-size: var(--jx-fs-micro);
  text-transform: uppercase;
  letter-spacing: var(--jx-tracking-eyebrow);
  color: var(--jx-ink-muted);
  padding: var(--jx-space-4) var(--jx-space-3) var(--jx-space-2);
  font-feature-settings: var(--jx-font-features-mono);
  list-style: none;
  cursor: default;
  border-top: 1px solid var(--jx-rule);
  margin-top: var(--jx-space-2);
}
.nav-category:first-child {
  border-top: none;
  margin-top: 0;
}

/* ── Content area ── */
.content {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--jx-space-7) var(--jx-gutter) var(--jx-space-8);
}

/* Article prose */
.content h1 { margin-top: 0; }
.content h2 { margin-top: var(--jx-space-7); }
.content h3 { margin-top: var(--jx-space-6); }

.content table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--jx-fs-sm);
  margin-block: var(--jx-space-5);
}
.content th,
.content td {
  text-align: left;
  padding: var(--jx-space-3) var(--jx-space-4);
  border-bottom: 1px solid var(--jx-rule);
}
.content th {
  font-family: var(--jx-font-mono);
  font-size: var(--jx-fs-xs);
  text-transform: uppercase;
  letter-spacing: var(--jx-tracking-eyebrow);
  color: var(--jx-ink-muted);
  font-weight: var(--jx-weight-heading);
  border-bottom: 1px solid var(--jx-rule-strong);
  font-feature-settings: var(--jx-font-features-mono);
}
.content tr:hover { background: var(--jx-rule-soft); }

/* Lists in content */
.content ul, .content ol {
  padding-left: var(--jx-space-5);
}
.content li {
  margin-bottom: var(--jx-space-2);
}
.content li::marker {
  color: var(--jx-ink-muted);
}

/* Images */
.content img {
  max-width: 100%;
  border-radius: var(--jx-radius-3);
  box-shadow: var(--jx-shadow-hairline);
}

/* ── Home page hero ── */
.hero {
  margin-bottom: var(--jx-space-7);
}
.hero h1 {
  font-size: var(--jx-fs-h1);
  line-height: var(--jx-leading-display);
  letter-spacing: var(--jx-tracking-h1);
  margin-bottom: var(--jx-space-4);
}
.hero .lede {
  font-size: var(--jx-fs-lg);
  color: var(--jx-ink-2);
  line-height: var(--jx-leading-body);
  max-width: var(--jx-measure-lede);
}

/* Stats grid on home page */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--jx-space-4);
  margin-block: var(--jx-space-6);
}
.stat-card {
  padding: var(--jx-space-5);
  background: var(--jx-surface);
  border-radius: var(--jx-radius-4);
  box-shadow: var(--jx-shadow-stack);
}
.stat-card .stat-value {
  font-family: var(--jx-font-display);
  font-size: var(--jx-fs-h2);
  font-weight: var(--jx-weight-heading);
  color: var(--jx-accent);
  letter-spacing: var(--jx-tracking-h2);
}
.stat-card .stat-label {
  font-family: var(--jx-font-mono);
  font-size: var(--jx-fs-micro);
  text-transform: uppercase;
  letter-spacing: var(--jx-tracking-eyebrow);
  color: var(--jx-ink-muted);
  margin-top: var(--jx-space-2);
  font-feature-settings: var(--jx-font-features-mono);
}

/* Track cards grid */
.track-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--jx-space-5);
  margin-block: var(--jx-space-6);
}
.track-card {
  padding: var(--jx-space-5);
  background: var(--jx-surface);
  border-radius: var(--jx-radius-4);
  box-shadow: var(--jx-shadow-stack);
  text-decoration: none;
  color: var(--jx-ink);
  transition: box-shadow var(--jx-duration-base) var(--jx-easing),
              transform var(--jx-duration-base) var(--jx-easing);
}
.track-card:hover {
  box-shadow: var(--jx-shadow-stack), 0 4px 16px rgba(26,122,109,0.12);
  transform: translateY(-2px);
}
.track-card h3 {
  font-size: var(--jx-fs-lg);
  margin: 0 0 var(--jx-space-2);
}
.track-card .track-meta {
  font-family: var(--jx-font-mono);
  font-size: var(--jx-fs-micro);
  color: var(--jx-ink-muted);
  text-transform: uppercase;
  letter-spacing: var(--jx-tracking-eyebrow);
  font-feature-settings: var(--jx-font-features-mono);
}
.track-card p {
  font-size: var(--jx-fs-sm);
  color: var(--jx-ink-2);
  margin: var(--jx-space-3) 0 0;
  line-height: var(--jx-leading-body);
}

/* Breadcrumb */
.breadcrumb {
  font-family: var(--jx-font-mono);
  font-size: var(--jx-fs-xs);
  color: var(--jx-ink-muted);
  letter-spacing: var(--jx-tracking-mono);
  margin-bottom: var(--jx-space-5);
  font-feature-settings: var(--jx-font-features-mono);
}
.breadcrumb a {
  color: var(--jx-ink-muted);
  text-decoration: none;
}
.breadcrumb a:hover { color: var(--jx-accent); }
.breadcrumb .sep { margin: 0 var(--jx-space-2); }

/* ── Responsive ── */
@media (max-width: 860px) {
  .topbar-search {
    max-width: none;
    flex: 1 1 auto;
  }
  .topbar .jx-return-to-hub {
    display: none;
  }
  .shell {
    grid-template-columns: 1fr;
  }
  .sidebar {
    position: fixed;
    left: 0;
    top: var(--rb-topbar-h);
    width: var(--rb-sidebar-w);
    transform: translateX(-100%);
    transition: transform var(--jx-duration-base) var(--jx-easing);
    z-index: 90;
    box-shadow: none;
  }
  .sidebar.open {
    transform: translateX(0);
    box-shadow: 4px 0 24px rgba(0,0,0,0.08);
  }
  .menu-toggle { display: block; }
  .content {
    padding: var(--jx-space-5) var(--jx-gutter) var(--jx-space-7);
  }
  .hero h1 {
    font-size: var(--jx-fs-h2);
  }
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (max-width: 480px) {
  .stats-grid {
    grid-template-columns: 1fr;
  }
  .track-grid {
    grid-template-columns: 1fr;
  }
}

/* ── Skip link ── */
.skip-link {
  position: absolute;
  top: -999px;
  left: var(--jx-space-4);
  padding: var(--jx-space-2) var(--jx-space-4);
  background: var(--jx-accent);
  color: var(--jx-surface);
  border-radius: var(--jx-radius-2);
  z-index: 999;
  text-decoration: none;
  font-size: var(--jx-fs-sm);
}
.skip-link:focus {
  top: var(--jx-space-2);
}

/* ── Active trail (parent/grandparent highlight) ── */
.nav-list a.active-trail {
  color: var(--jx-accent);
  font-weight: var(--jx-weight-ui);
}

/* ── Sidebar overlay (mobile) ── */
.sidebar-overlay {
  display: none;
}
@media (max-width: 860px) {
  .sidebar-overlay {
    display: block;
    position: fixed;
    inset: 0;
    top: var(--rb-topbar-h);
    background: rgba(0, 0, 0, 0.3);
    z-index: 80;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--jx-duration-base) var(--jx-easing);
  }
  .sidebar-overlay.visible {
    opacity: 1;
    pointer-events: auto;
  }
  body.sidebar-open {
    overflow: hidden;
  }
}

/* ── Sidebar collapse/expand ── */
.nav-children.collapsed {
  display: none;
}
.nav-item-row {
  display: flex;
  align-items: center;
}
.nav-item-row > a {
  flex: 1;
  min-width: 0;
}
.nav-toggle {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--jx-ink-muted);
  font-size: var(--jx-fs-xs);
  width: 24px;
  height: 24px;
  padding: 0;
  margin-left: var(--jx-space-1);
  border-radius: var(--jx-radius-2);
  transition: background var(--jx-duration-fast) var(--jx-easing),
              color var(--jx-duration-fast) var(--jx-easing);
}
.nav-toggle:hover {
  background: var(--jx-accent-tint);
  color: var(--jx-accent);
}

/* ── Page navigation (prev/next) ── */
.page-nav {
  display: flex;
  justify-content: space-between;
  gap: var(--jx-space-4);
  margin-top: var(--jx-space-8);
  padding-top: var(--jx-space-6);
  border-top: 1px solid var(--jx-rule);
}
.page-nav__prev,
.page-nav__next {
  display: flex;
  flex-direction: column;
  gap: var(--jx-space-1);
  text-decoration: none;
  color: var(--jx-ink);
  padding: var(--jx-space-3) var(--jx-space-4);
  border-radius: var(--jx-radius-3);
  transition: background var(--jx-duration-fast) var(--jx-easing);
  max-width: 45%;
}
.page-nav__next {
  text-align: right;
  margin-left: auto;
}
.page-nav__prev:hover,
.page-nav__next:hover {
  background: var(--jx-accent-tint);
}
.page-nav__label {
  font-family: var(--jx-font-mono);
  font-size: var(--jx-fs-micro);
  text-transform: uppercase;
  letter-spacing: var(--jx-tracking-eyebrow);
  color: var(--jx-ink-muted);
  font-feature-settings: var(--jx-font-features-mono);
}
.page-nav__title {
  font-size: var(--jx-fs-sm);
  font-weight: var(--jx-weight-ui);
  color: var(--jx-accent);
  line-height: 1.3;
}
.page-nav__disabled {
  visibility: hidden;
}
@media (max-width: 480px) {
  .page-nav {
    flex-direction: column;
    gap: var(--jx-space-3);
  }
  .page-nav__prev,
  .page-nav__next {
    max-width: 100%;
    text-align: left;
    margin-left: 0;
  }
}

/* ── Back to top button ── */
.back-to-top {
  position: fixed;
  bottom: var(--jx-space-6);
  right: var(--jx-space-6);
  z-index: 50;
  width: 40px;
  height: 40px;
  border-radius: var(--jx-radius-pill);
  border: 1px solid var(--jx-rule);
  background: var(--jx-surface);
  color: var(--jx-accent);
  font-size: var(--jx-fs-lg);
  cursor: pointer;
  box-shadow: var(--jx-shadow-stack);
  transition: opacity var(--jx-duration-fast) var(--jx-easing),
              transform var(--jx-duration-fast) var(--jx-easing);
  display: flex;
  align-items: center;
  justify-content: center;
}
.back-to-top:hover {
  transform: translateY(-2px);
  box-shadow: var(--jx-shadow-stack), 0 4px 12px rgba(0,0,0,0.08);
}
.back-to-top[hidden] {
  display: none;
}

/* ── Table responsive wrapper ── */
.table-wrapper {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin-block: var(--jx-space-5);
}
.table-wrapper table {
  margin-block: 0;
}

/* ── Focus visible (a11y) ── */
.track-card:focus-visible,
.nav-list a:focus-visible,
.page-nav__prev:focus-visible,
.page-nav__next:focus-visible {
  outline: 2px solid var(--jx-accent);
  outline-offset: 2px;
}

/* ── Touch target improvements (mobile) ── */
@media (max-width: 860px) {
  .nav-list a {
    min-height: 44px;
    display: flex;
    align-items: center;
  }
  .nav-list .nav-children a {
    min-height: 40px;
  }
  .nav-toggle {
    width: 32px;
    height: 32px;
  }
  .menu-toggle {
    min-width: 44px;
    min-height: 44px;
  }
}

/* ── Mermaid diagram containers ── */
.mermaid-container {
  position: relative;
  margin-block: var(--jx-space-6);
  padding: var(--jx-space-5) var(--jx-space-4);
  background: var(--jx-surface);
  border: 1px solid var(--jx-rule);
  border-radius: var(--jx-radius-4);
  box-shadow: var(--jx-shadow-stack);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  transition: box-shadow var(--jx-duration-base) var(--jx-easing),
              border-color var(--jx-duration-base) var(--jx-easing);
}
.mermaid-container:hover {
  box-shadow: var(--jx-shadow-stack), 0 4px 20px rgba(26,122,109,0.10);
  border-color: var(--jx-accent);
}
@media (prefers-color-scheme: dark) {
  .mermaid-container:hover {
    box-shadow: var(--jx-shadow-stack), 0 4px 24px rgba(78,201,176,0.12);
  }
}

.mermaid-diagram {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 80px;
}
.mermaid-diagram svg {
  max-width: 100%;
  height: auto;
}

/* Expand button (top-right corner) */
.mermaid-expand {
  position: absolute;
  top: var(--jx-space-3);
  right: var(--jx-space-3);
  z-index: 2;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--jx-surface);
  border: 1px solid var(--jx-rule);
  border-radius: var(--jx-radius-2);
  color: var(--jx-ink-muted);
  cursor: pointer;
  opacity: 0;
  transition: opacity var(--jx-duration-fast) var(--jx-easing),
              background var(--jx-duration-fast) var(--jx-easing),
              color var(--jx-duration-fast) var(--jx-easing);
}
.mermaid-container:hover .mermaid-expand {
  opacity: 1;
}
.mermaid-expand:hover {
  background: var(--jx-accent-tint);
  color: var(--jx-accent);
  border-color: var(--jx-accent);
}

/* ── Mermaid lightbox (fullscreen view) ── */
.mermaid-lightbox {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--jx-duration-base) var(--jx-easing);
}
.mermaid-lightbox.active {
  opacity: 1;
  pointer-events: auto;
}
.mermaid-lightbox__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}
@media (prefers-color-scheme: dark) {
  .mermaid-lightbox__backdrop {
    background: rgba(0, 0, 0, 0.85);
  }
}
.mermaid-lightbox__body {
  position: relative;
  width: 94vw;
  max-width: 1600px;
  max-height: 92vh;
  padding: var(--jx-space-7);
  background: var(--jx-surface);
  border-radius: var(--jx-radius-4);
  box-shadow: 0 24px 64px rgba(0, 0, 0, 0.3);
  overflow: auto;
  animation: mermaid-lb-in var(--jx-duration-base) var(--jx-easing);
}
@keyframes mermaid-lb-in {
  from {
    transform: scale(0.92);
    opacity: 0;
  }
  to {
    transform: scale(1);
    opacity: 1;
  }
}
.mermaid-lightbox__content {
  display: flex;
  justify-content: center;
  align-items: center;
}
.mermaid-lightbox__content svg {
  max-width: 100%;
  max-height: 80vh;
  height: auto;
}
.mermaid-lightbox__close {
  position: absolute;
  top: var(--jx-space-3);
  right: var(--jx-space-3);
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--jx-surface);
  border: 1px solid var(--jx-rule);
  border-radius: var(--jx-radius-pill);
  color: var(--jx-ink-2);
  font-size: var(--jx-fs-lg);
  cursor: pointer;
  transition: background var(--jx-duration-fast) var(--jx-easing),
              color var(--jx-duration-fast) var(--jx-easing);
}
.mermaid-lightbox__close:hover {
  background: var(--jx-accent-tint);
  color: var(--jx-accent);
}

/* ── MathJax display formulas (kramdown math blocks) ── */
.content .MathJax_Display,
.content .MathJax {
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  max-width: 100%;
}
.content .MathJax_Display {
  margin-block: var(--jx-space-5);
  padding-block: var(--jx-space-2);
}
@media (prefers-color-scheme: dark) {
  .content .MathJax {
    color: var(--jx-ink);
  }
}