/* ==========================================================================
   base.css — site-wide elements and shared components
   Colours come only from the --zl-* tokens (assets/theme/*.scss), so
   nothing here needs a light/dark variant.
   ========================================================================== */

/* ---------- typography ----------
   Everything is sized in rem, so this one value sets the scale of the site
   (Quarto's default is 17px). Bootstrap reads it from --bs-root-font-size. */
:root {
  --bs-root-font-size: 19px;
  scroll-padding-top: 6rem;   /* anchor links land below the fixed navbar */
}
@media (max-width: 767.98px) {
  :root { --bs-root-font-size: 17px; }
}

body {
  font-feature-settings: "kern", "liga";
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6,
.h1, .h2, .h3, .h4, .h5, .h6 {
  color: var(--zl-ink);
  letter-spacing: -0.01em;
  line-height: 1.2;
}

/* section headings inside articles: serif with a hairline rule */
main.content h2:not(.quarto-appendix-heading):not(#toc-title) {
  margin-top: 3rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--zl-rule);
}

a { text-underline-offset: 0.2em; text-decoration-thickness: 1px; }
a:hover { color: var(--zl-accent); }

strong, b { color: var(--zl-ink); font-weight: 600; }

hr { border-color: var(--zl-rule); opacity: 1; }

::selection { background: color-mix(in srgb, var(--zl-accent) 25%, transparent); }

blockquote,
.blockquote {
  border-left: 2px solid var(--zl-accent);
  padding: 0.25rem 0 0.25rem 1.25rem;
  color: var(--zl-muted);
  font-family: var(--zl-serif);
  font-size: 1.15em;
  font-style: italic;
}

/* inline code + code blocks */
p code:not(.sourceCode),
li code:not(.sourceCode),
td code:not(.sourceCode) {
  padding: 0.1em 0.35em;
  border: 1px solid var(--zl-rule);
  border-radius: 3px;
  font-size: 0.88em;
}
div.sourceCode {
  border: 1px solid var(--zl-rule);
  border-radius: 4px;
}

/* tables */
.table, table { --bs-table-bg: transparent; color: var(--zl-text); }
.table > :not(caption) > * > * { border-bottom-color: var(--zl-rule); }
thead th {
  font-family: var(--zl-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--zl-muted);
}

/* callouts: flat, accent edge */
.callout {
  border: 1px solid var(--zl-rule) !important;
  border-left: 3px solid var(--zl-accent) !important;
  border-radius: 0 !important;
  background: transparent !important;
}
.callout .callout-header { background: transparent !important; }

/* ---------- small shared components ---------- */

/* mono label with a leading rule: "—— RESEARCH" */
.zl-eyebrow,
body p.zl-eyebrow {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin: 0 0 1.25rem;
  font-family: var(--zl-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--zl-accent);
}
.zl-eyebrow::before {
  content: "";
  flex: none;
  width: 2.25rem;
  height: 1px;
  background: currentColor;
}

/* outlined button that fills on hover.
   `body a.zl-cta` outranks Bootstrap's link colour rules. */
body a.zl-cta,
.quarto-title-block .btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1.4rem;
  font-family: var(--zl-mono);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.16em;
  line-height: 1.2;
  text-transform: uppercase;
  white-space: nowrap;
  color: var(--zl-accent);
  background: transparent;
  text-decoration: none;
  border: 1px solid var(--zl-accent);
  border-radius: 0;
  transition: background-color 0.3s ease, color 0.3s ease;
}
body a.zl-cta:hover,
.quarto-title-block .btn-secondary:hover {
  background-color: var(--zl-accent);
  color: var(--zl-bg);
  border-color: var(--zl-accent);
}
body a.zl-cta .zl-cta__arrow {
  display: inline-block;
  color: inherit;
  transition: transform 0.3s ease;
}
body a.zl-cta:hover .zl-cta__arrow { transform: translateX(0.35rem); }

/* ---------- navbar ----------
   Fixed metrics so the bar is identical in both colour schemes. */
.navbar {
  min-height: 76px;
  padding: 0.75rem 0;
  background: var(--zl-bg);
  border: none;
  box-shadow: none;
}
.navbar .navbar-container {
  padding-left: var(--zl-gutter);
  padding-right: var(--zl-gutter);
}
.navbar .navbar-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  margin: 0;
  padding: 0;
}
.navbar .navbar-brand-logo { margin-right: 0.65rem; }
.navbar .navbar-logo {
  height: 26px;
  width: auto;
  max-height: none;
  padding: 0;
  margin: 0;
}
body.quarto-dark .navbar .navbar-logo {
  /* transparent ink mark → cream text tone */
  filter: brightness(0) invert(1) sepia(0.15) brightness(0.93);
}
.navbar .navbar-title {
  font-family: var(--zl-sans);
  font-size: 1rem;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--zl-ink);
}
.navbar .navbar-nav .nav-link {
  margin: 0 0.4rem;
  padding: 0.5rem 0.6rem;
  font-size: 0.95rem;
  font-weight: 500;
  letter-spacing: 0.14em;
  line-height: 1.2;
  text-transform: uppercase;
  color: var(--zl-muted);
  /* underline drawn with a shadow so hover never changes the box size */
  box-shadow: inset 0 -1px 0 transparent;
  transition: color 0.2s ease, box-shadow 0.2s ease;
}
.navbar .navbar-nav .nav-link:hover,
.navbar .navbar-nav .nav-link.active {
  color: var(--zl-ink);
  box-shadow: inset 0 -1px 0 var(--zl-accent);
}
.navbar .quarto-navbar-tools {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  margin-left: 0.75rem;
}
.navbar .quarto-navbar-tools .nav-link,
.navbar .quarto-navbar-tools .quarto-color-scheme-toggle,
.navbar #quarto-search .aa-DetachedSearchButton {
  margin: 0;
  padding: 0.4rem;
  box-shadow: none;
  font-size: 1.05rem;
  line-height: 1;
  color: var(--zl-muted);
}
.navbar .quarto-navbar-tools .bi,
.navbar .quarto-navbar-tools svg {
  width: 1.05rem;
  height: 1.05rem;
  font-size: 1.05rem;
  line-height: 1;
}
.navbar .dropdown-menu {
  padding: 0.5rem 0;
  background: var(--zl-bg);
  border: 1px solid var(--zl-rule);
  border-radius: 0;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.08);
}
.navbar .dropdown-item {
  font-size: 0.9rem;
  color: var(--zl-text);
}
.navbar .dropdown-item:hover,
.navbar .dropdown-item:focus {
  background: var(--zl-surface);
  color: var(--zl-accent);
}

/* navbar stays pinned to the top while scrolling; Quarto's headroom script
   would otherwise slide it away on scroll-down */
#quarto-header.fixed-top { position: fixed; }
#quarto-header.headroom { transform: none !important; }
#quarto-header .navbar {
  transition: background-color 0.3s ease, box-shadow 0.3s ease;
}
/* 992–1200px: full menu still shown but tight on space */
@media (min-width: 992px) and (max-width: 1199.98px) {
  .navbar .navbar-nav .nav-link { margin: 0 0.1rem; font-size: 0.85rem; letter-spacing: 0.08em; }
}
.navbar .navbar-brand-container,
.navbar .navbar-brand { flex-shrink: 0; }

/* hairline once the page has scrolled (shadow, so the bar never changes size) */
#quarto-header.headroom--not-top .navbar { box-shadow: 0 1px 0 var(--zl-rule); }

/* homepage: transparent over the hero, solid once scrolled */
body.zl-home #quarto-header.headroom--top .navbar { background: transparent; }

/* ---------- footer ---------- */
.nav-footer {
  min-height: 0;
  margin-top: 4rem;
  padding: 2rem var(--zl-gutter);
  border-top: 1px solid var(--zl-rule);
  background: var(--zl-bg);
  font-size: 1rem;
  letter-spacing: 0.02em;
  color: var(--zl-muted);
}
.nav-footer p { margin: 0; }
/* room under the footer text for the floating "Back to top" button */
.nav-footer { padding-bottom: 5rem; }
#quarto-back-to-top {
  bottom: 1.25rem;
  padding: 0.4rem 0.9rem;
  font-family: var(--zl-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--zl-muted);
  background: var(--zl-bg);
  border: 1px solid var(--zl-rule);
  border-radius: 0;
  box-shadow: none;
}
#quarto-back-to-top:hover { color: var(--zl-accent); border-color: var(--zl-accent); }
/* Quarto shrinks each footer column to 0.825em; keep them at full size */
.nav-footer .nav-footer-left,
.nav-footer .nav-footer-center,
.nav-footer .nav-footer-right { font-size: 1rem; }
.nav-footer a { color: var(--zl-muted); }
.nav-footer a:hover { color: var(--zl-accent); }
.nav-footer .zl-footer-icon {
  margin-left: 0.75rem;
  font-size: 1.35rem;
  color: var(--zl-muted);
  text-decoration: none;
}
.nav-footer .zl-footer-icon:hover { color: var(--zl-accent); }

/* WeChat: QR card pops up above the icon on hover / tap (focus) */
.zl-wechat { position: relative; display: inline-block; cursor: pointer; outline: none; }
.zl-wechat:hover .zl-footer-icon,
.zl-wechat:focus-within .zl-footer-icon { color: var(--zl-accent); }
.zl-wechat__card {
  position: absolute;
  right: -0.5rem;
  bottom: calc(100% + 0.75rem);
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  width: 10.5rem;
  padding: 0.9rem 0.9rem 0.75rem;
  background: var(--zl-bg);
  border: 1px solid var(--zl-rule);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.12);
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  color: var(--zl-muted);
  white-space: nowrap;
  opacity: 0;
  visibility: hidden;
  transform: translateY(6px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
}
.zl-wechat__card img { width: 100%; height: auto; }
.zl-wechat:hover .zl-wechat__card,
.zl-wechat:focus .zl-wechat__card,
.zl-wechat:focus-within .zl-wechat__card {
  opacity: 1;
  visibility: visible;
  transform: none;
}
@media (max-width: 991.98px) {
  .nav-footer { flex-direction: column; gap: 0.75rem; text-align: center; }
  .nav-footer > div { flex-basis: auto; text-align: center; }
}

/* ---------- index-page header (News, Blog, Team, ...) ----------
   Pages opt in with `body-classes: zl-index`. The page's `subtitle`
   becomes the mono eyebrow above the title. */
body.zl-index #title-block-header {
  display: block;
  margin: 2.5rem 0 3rem;
  padding: 0 0 2.25rem;
  border-bottom: 1px solid var(--zl-rule);
  background: none;
}
body.zl-index #title-block-header .quarto-title {
  display: flex;
  flex-direction: column;
  padding: 0 !important;
  background: none !important;
  box-shadow: none !important;
  color: var(--zl-ink);
}
body.zl-index #title-block-header .title {
  order: 2;
  margin: 0;
  padding: 0;
  border: none;
  font-size: clamp(2.6rem, 5vw, 4rem);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.025em;
  color: var(--zl-ink);
  text-align: left;
}
body.zl-index #title-block-header .subtitle {
  order: 1;
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin: 0 0 1.25rem;
  font-family: var(--zl-mono);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--zl-accent);
}
body.zl-index #title-block-header .subtitle::before {
  content: "";
  width: 2.25rem;
  height: 1px;
  background: currentColor;
}
body.zl-index #title-block-header.quarto-title-block.default .description {
  max-width: 40rem;
  margin: 1.75rem 0 0;
  padding: 0 !important;
  font-size: 1.1rem;
  line-height: 1.65;
  color: var(--zl-muted);
  text-align: left;
}
body.zl-index #title-block-header .description p { margin: 0; }
body.zl-index #title-block-header.quarto-title-block.default .quarto-title-meta { display: none; }

/* ---------- article title banner (posts, publications, news) ----------
   The partial puts the featured image behind the title; the overlay
   colour comes from --zl-banner. */
.quarto-title-block .featured-image {
  background-size: cover;
  background-position: center;
  box-shadow: inset 0 0 0 100vmax var(--zl-banner);
  color: #f4f0e8;
}
body:not(.zl-index) .quarto-title-block .featured-image {
  padding: 4.5rem 0 3.5rem !important;
}
.quarto-title-block .featured-image .title {
  font-size: clamp(2.2rem, 4.5vw, 3.5rem);
  font-weight: 600;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: #f4f0e8;
}
.quarto-title-block .featured-image .subtitle {
  max-width: 46rem;
  margin-top: 1.25rem;
  font-size: 1.2rem;
  line-height: 1.55;
  color: rgba(244, 240, 232, 0.85);
}
.quarto-title-block .featured-image .quarto-categories {
  margin-top: 1.75rem;
  gap: 0.5rem;
}
.quarto-title-block .featured-image .quarto-category {
  padding: 0.3rem 0.65rem;
  font-family: var(--zl-mono);
  font-size: 0.7rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: #f4f0e8;
  background: transparent;
  border: 1px solid rgba(244, 240, 232, 0.45);
  border-radius: 0;
  opacity: 1;
}

/* metadata row under the banner (Author / Published) */
.quarto-title-meta {
  gap: 1.5rem 3rem;
  margin-top: 2rem;
}
.quarto-title-meta-heading {
  margin-bottom: 0.35rem;
  font-family: var(--zl-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--zl-muted);
}
.quarto-title-meta-contents p { margin: 0; color: var(--zl-ink); }

/* link buttons (Publication / Preprint / Code ...), aligned with the metadata row */
.quarto-title-block [aria-label="Links"] {
  grid-column: page-start / body-content-end;
  gap: 0.6rem !important;
  margin-top: 2rem !important;
}
.quarto-title-block .btn-secondary {
  padding: 0.6rem 1rem;
  font-size: 0.72rem;
}
.quarto-title-block .btn-secondary .bi {
  width: 1em;
  height: 1em;
  margin: 0 !important;
  font-size: 1em;
  line-height: 1;
}

/* ---------- table of contents ---------- */
#TOC #toc-title,
#quarto-margin-sidebar .quarto-listing-category-title {
  margin: 0 0 1rem;
  font-family: var(--zl-mono);
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--zl-accent);
}
#TOC ul { border-left: 1px solid var(--zl-rule); }
#quarto-margin-sidebar #TOC a.nav-link {
  margin-left: -1px;
  padding: 0.3rem 0 0.3rem 1rem;
  font-size: 0.85rem;
  line-height: 1.4;
  color: var(--zl-muted);
  border-left: 2px solid transparent;
}
#quarto-margin-sidebar #TOC a.nav-link:hover { color: var(--zl-ink); }
/* current section: bold ink with an accent bar */
#quarto-margin-sidebar #TOC a.nav-link.active {
  font-weight: 600;
  color: var(--zl-ink);
  border-left-color: var(--zl-accent);
}
.sidebar,
#quarto-margin-sidebar { border: none; box-shadow: none; background: transparent; }

/* The navbar never hides, but Quarto's script still moves sticky sidebars to
   top:0 when it thinks the bar slid away; keep them below the 76px bar. */
#quarto-margin-sidebar.sidebar,
#quarto-sidebar.sidebar {
  top: calc(76px + 1.5rem) !important;
  max-height: calc(100vh - 76px - 3rem) !important;
}

/* ---------- pagination ---------- */
.pagination .page-link {
  font-family: var(--zl-mono);
  font-size: 0.8rem;
  color: var(--zl-ink);
  background: transparent;
  border-color: var(--zl-rule);
  border-radius: 0 !important;
}
.pagination .page-link:hover,
.pagination .page-item.active .page-link {
  color: var(--zl-bg);
  background: var(--zl-ink);
  border-color: var(--zl-ink);
}