/* CFD project page. Visual language follows the LatSearch project page
   (https://zengqunzhao.github.io/LatSearch.html): light hero, blue accent,
   left-ruled section titles, carded figures and tables. */

:root {
  --accent: #2563eb;
  --accent-dark: #1d4ed8;
  --accent-light: #eff6ff;
  --accent-mid: #bfdbfe;
  --text-primary: #0a1628;
  --text-secondary: #1e3a5f;
  --text-muted: #52647a;
  --border: #e2e8f0;
  --rule: #cbd5e1;
  --background: #ffffff;
  --background-subtle: #f8fafc;
  --radius: 8px;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.07);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, 0.09);
  --paper-width: 1120px;
  --nav-height: 58px;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text-primary);
  background: var(--background);
  font-family: "Noto Sans", "Inter", "Segoe UI", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  overflow-x: clip;
}

*, *::before, *::after { box-sizing: border-box; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { display: block; max-width: 100%; height: auto; }
:focus-visible { outline: 3px solid var(--accent-dark); outline-offset: 3px; }

.skip-link {
  position: fixed;
  top: 8px;
  left: 12px;
  z-index: 200;
  padding: 7px 11px;
  border-radius: 6px;
  color: #fff;
  background: var(--accent);
  font-size: 13px;
  font-weight: 600;
  transform: translateY(-160%);
  transition: transform 0.15s;
}
.skip-link:focus { color: #fff; transform: translateY(0); text-decoration: none; }

.container {
  width: min(var(--paper-width), calc(100% - 48px));
  margin: 0 auto;
}

.main-content { padding-top: var(--nav-height); }

/* Navigation */
.nav-top {
  position: fixed;
  inset: 0 0 auto;
  z-index: 100;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 24px;
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid rgba(226, 232, 240, 0.9);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
}
.nav-inner {
  width: 100%;
  max-width: var(--paper-width);
  min-width: 0;
  display: flex;
  align-items: center;
  gap: 20px;
}
.nav-left {
  flex: 0 0 auto;
  margin-right: auto;
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
}
.nav-home {
  color: var(--text-muted);
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 0.08em;
}
.nav-home:hover { color: var(--accent); text-decoration: none; }
.nav-sep { color: #cbd5e1; font-size: 14px; }
.nav-brand {
  flex: 0 0 auto;
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: -0.01em;
  white-space: nowrap;
}
.nav-brand:hover { color: var(--accent); text-decoration: none; }
.nav-links {
  min-width: 0;
  display: flex;
  align-items: center;
  gap: 2px;
  overflow-x: auto;
  scrollbar-width: none;
}
.nav-links::-webkit-scrollbar { display: none; }
.nav-links a {
  flex: 0 0 auto;
  padding: 6px 10px;
  border-radius: 999px;
  color: var(--text-muted);
  font-size: 12.5px;
  font-weight: 500;
  line-height: 1.4;
  white-space: nowrap;
  transition: color 0.15s, background 0.15s;
}
.nav-links a:hover { color: var(--accent); text-decoration: none; }
.nav-links a.active { color: var(--accent); background: var(--accent-light); }

/* Hero */
.hero {
  position: relative;
  z-index: 0;
  isolation: isolate;
  padding: 56px 24px 40px;
  text-align: center;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0 calc(50% - 50vw);
  z-index: -1;
  border-bottom: 1px solid #dfe4ec;
  background: linear-gradient(180deg, #fbfcff 0%, #eef3f8 100%);
}
.hero h1 {
  max-width: 980px;
  margin: 0 auto;
  color: #363636;
  font-size: 2.35rem;
  font-weight: 750;
  line-height: 1.18;
  text-wrap: balance;
}
.venue-badge {
  display: inline-flex;
  align-items: center;
  margin: 16px auto 0;
  padding: 4px 12px;
  border-radius: 999px;
  color: #fff;
  background: var(--accent);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
}
.authors-block { max-width: 980px; margin: 16px auto 0; }
.authors-names {
  margin: 0;
  color: var(--text-secondary);
  font-size: 16.8px;
  line-height: 1.7;
  text-wrap: balance;
}
.author-block { display: inline-block; margin: 0 0.12rem; white-space: nowrap; }
.author-block:not(:last-child)::after {
  content: "\00b7";
  margin-left: 0.48rem;
  color: var(--text-muted);
}
.authors-names sup,
.authors-affiliations sup,
.authors-note sup {
  margin-left: 1px;
  color: var(--text-muted);
  font-size: 0.68em;
  font-weight: 600;
}
.authors-affiliations {
  margin: 0.6rem auto 0;
  color: var(--text-muted);
  font-size: 15.2px;
  line-height: 1.6;
}
.affiliation-block { display: inline-block; margin: 0 0.45rem; }
.authors-note { margin: 0.25rem 0 0; color: var(--text-muted); font-size: 13px; }
.author-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 20px;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  min-width: 112px;
  margin: 4px;
  padding: 8px 16px;
  border: 1px solid #303846;
  border-radius: 999px;
  color: #fff;
  background: #303846;
  font-size: 13px;
  font-weight: 600;
  line-height: 1.4;
  transition: border-color 0.15s, background 0.15s, transform 0.15s;
}
.btn:hover {
  color: #fff;
  border-color: var(--accent-dark);
  background: var(--accent-dark);
  transform: translateY(-1px);
  text-decoration: none;
}
.btn-icon { width: 14px; height: 14px; }

/* Sections */
.section {
  padding: 48px 0;
  border-top: 1px solid var(--border);
  scroll-margin-top: calc(var(--nav-height) + 16px);
}
.hero + .section { border-top: 0; }
.section-title {
  position: relative;
  margin: 0 0 24px;
  padding-left: 13px;
  color: var(--text-primary);
  font-size: clamp(1.35rem, 2.4vw, 1.75rem);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.025em;
}
.section-title::before {
  content: "";
  position: absolute;
  top: 0.12em;
  bottom: 0.12em;
  left: 0;
  width: 3px;
  border-radius: 999px;
  background: var(--accent);
}
.subsection-title {
  margin: 38px 0 16px;
  padding-bottom: 9px;
  border-bottom: 1px solid var(--border);
  color: var(--text-primary);
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -0.015em;
  scroll-margin-top: calc(var(--nav-height) + 16px);
}
.section-title + .subsection-title { margin-top: 0; }
.section p,
.section li {
  color: var(--text-secondary);
  font-size: 15.5px;
  line-height: 1.78;
  text-wrap: pretty;
}
.section p { margin: 0 0 14px; }
.section ul,
.section ol { margin: 0 0 14px; padding-left: 1.4em; }
.section li { margin-bottom: 6px; }
.section li::marker { color: var(--accent); font-weight: 700; }
.section b,
.section strong { color: var(--text-primary); }
/* Memory tiers: label colours match the borders in the framework figure. */
.section b.tier-event { color: #666666; }
.section b.tier-clip { color: #d79b00; }
.section b.tier-visual { color: #6c8ebf; }

.takeaway {
  padding: 18px 20px;
  border: 1px solid var(--accent-mid);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius);
  background: var(--accent-light);
}
.section p.takeaway { margin-bottom: 24px; font-size: 16px; line-height: 1.72; }

.highlights {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 22px 0 26px;
}
.highlight {
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--background-subtle);
}
.highlight-index {
  display: block;
  margin-bottom: 7px;
  color: var(--accent);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.highlight h3 {
  margin: 0 0 6px;
  color: var(--text-primary);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
}
.section .highlight p {
  margin: 0;
  color: var(--text-muted);
  font-size: 13.5px;
  line-height: 1.6;
}

/* Reasoning-loop flow */
.flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 4px;
  margin: 4px 0 12px;
}
.flow .step {
  margin: 0;
  padding: 4px 9px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text-secondary);
  background: var(--background-subtle);
  font-size: 12px;
  font-weight: 600;
  line-height: 1.4;
  white-space: nowrap;
}
.flow .step.router { color: var(--accent); border-color: var(--accent-mid); background: var(--accent-light); }
.flow .arrow { color: var(--text-muted); font-size: 13px; }
.section .flow-note { color: var(--text-muted); font-size: 13.5px; }
.flow .step.no { color: #9f2d20; border-color: #f0b8b3; background: #fdeceb; }
.flow .step.yes { color: #23632a; border-color: #a9d79c; background: #e8f5e4; }

/* Question and trajectory band on top of a qualitative figure */
.figure-top {
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
  background: var(--background-subtle);
}
.section .figure-question { margin: 0 0 10px; color: var(--text-secondary); font-size: 14px; line-height: 1.6; }
.figure-question .options { color: var(--text-muted); font-size: 13px; }
.figure-top .flow { margin: 0; }

/* Figures and tables */
.figure-block {
  overflow: hidden;
  margin: 22px 0 26px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: #fff;
  box-shadow: var(--shadow-sm);
}
.figure-block > img,
.figure-block > a > img {
  width: 100%;
  background: #fff;
}
.figure-block > img { padding: 12px; }
.figure-block.narrow { max-width: 760px; }
.figure-block.small { max-width: 520px; }
.figure-block.medium { max-width: 900px; }
.figure-caption {
  margin: 0;
  padding: 14px 18px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  background: var(--background-subtle);
  font-size: 13px;
  line-height: 1.6;
  text-align: left;
}
.figure-caption b { color: var(--text-secondary); }
.figure-pair {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 2fr);
  gap: 16px;
  align-items: start;
  margin: 22px 0 26px;
}
.figure-pair .figure-block { margin: 0; }

.table-scroll { overflow-x: auto; }
.paper-table {
  width: 100%;
  border-collapse: collapse;
  color: var(--text-secondary);
  font-size: 13px;
  line-height: 1.45;
  font-variant-numeric: tabular-nums;
}
.paper-table th,
.paper-table td {
  padding: 7px 10px;
  text-align: center;
  vertical-align: middle;
  white-space: nowrap;
}
.paper-table thead th {
  color: var(--text-primary);
  background: var(--background-subtle);
  font-weight: 600;
  white-space: normal;
  border-bottom: 1px solid var(--rule);
}
.paper-table thead tr:not(:last-child) th[colspan] { border-bottom: 1px solid var(--border); }
.paper-table tbody td { border-bottom: 1px solid #eef2f7; }
.paper-table tbody tr:last-child td { border-bottom: 0; }
.paper-table th:first-child,
.paper-table td:first-child { text-align: left; }
.ctr-first .paper-table th:first-child,
.ctr-first .paper-table td:first-child { text-align: center; }
.paper-table tr.grp td {
  color: var(--text-muted);
  background: #fbfcfe;
  font-size: 12px;
  font-style: italic;
}
.paper-table tr.ours td { color: var(--text-primary); background: var(--accent-light); }
.paper-table tr.muted td { color: #9aa5b1; }

.zoomable { cursor: zoom-in; }

/* BibTeX */
.bibtex-box {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--background-subtle);
}
.bibtex-box pre {
  margin: 0;
  padding: 24px 78px 24px 24px;
  overflow-x: auto;
  color: var(--text-secondary);
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 12.5px;
  line-height: 1.65;
}
.copy-btn {
  position: absolute;
  top: 12px;
  right: 12px;
  padding: 5px 9px;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  background: rgba(255, 255, 255, 0.94);
  font: inherit;
  font-size: 11px;
  font-weight: 600;
  cursor: pointer;
}
.copy-btn:hover { color: var(--accent); border-color: var(--accent-mid); background: var(--accent-light); }

/* Footer and utilities */
.paper-footer {
  max-width: var(--paper-width);
  margin: 24px auto 0;
  padding: 24px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 12px;
  text-align: center;
}
.paper-footer p { margin: 0; }
.paper-footer a { color: var(--text-secondary); font-weight: 600; }

.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  z-index: 90;
  width: 38px;
  height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  border-radius: 50%;
  color: var(--text-secondary);
  background: rgba(255, 255, 255, 0.94);
  box-shadow: var(--shadow-md);
  font-size: 17px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(6px);
  transition: opacity 0.15s, transform 0.15s, color 0.15s, background 0.15s;
}
.back-to-top.show { opacity: 1; visibility: visible; transform: translateY(0); }
.back-to-top:hover { color: #fff; border-color: var(--accent); background: var(--accent); }

.image-viewer {
  width: min(96vw, 1500px);
  max-width: none;
  max-height: 94vh;
  padding: 0;
  border: 0;
  border-radius: var(--radius);
  background: transparent;
  box-shadow: var(--shadow-md);
  overflow: auto;
}
.image-viewer::backdrop { background: rgba(2, 6, 23, 0.82); }
.image-viewer img { width: 100%; border-radius: var(--radius); background: #fff; }
.image-viewer-close {
  position: fixed;
  top: 16px;
  right: 16px;
  width: 38px;
  height: 38px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 50%;
  color: #fff;
  background: rgba(15, 23, 42, 0.78);
  font-size: 22px;
  line-height: 1;
  cursor: pointer;
}

/* Responsive */
@media (max-width: 900px) {
  .hero h1 { font-size: 1.85rem; }
  .highlights { grid-template-columns: 1fr; }
  .figure-pair { grid-template-columns: 1fr; }
}
@media (max-width: 720px) {
  :root { --nav-height: 54px; }
  .container { width: calc(100% - 32px); }
  .nav-top { padding: 0 16px; }
  .nav-inner { gap: 10px; }
  .nav-brand, .nav-sep { font-size: 13px; }
  .nav-home { font-size: 11.5px; }
  .nav-links a { padding: 5px 8px; font-size: 11.5px; }
  .hero { padding: 38px 8px 32px; }
  .hero h1 { font-size: 1.45rem; }
  .section { padding: 38px 0; }
  .figure-block > img { padding: 6px; }
  .bibtex-box pre { padding: 54px 18px 18px; font-size: 11.5px; }
}
@media (max-width: 480px) {
  .container { width: calc(100% - 24px); }
  .authors-names { font-size: 15px; }
  .authors-affiliations { font-size: 14px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  * { transition-duration: 0.01ms !important; }
}