:root {
  /* Colors */
  --color-bg:             #FFFFFF;
  --color-surface:        #F7F8FA;
  --color-border:         #E2E5EA;
  --color-text-primary:   #0F1117;
  --color-text-secondary: #4B5563;
  --color-text-muted:     #9CA3AF;
  --color-accent:         #1D6FA4;
  --color-accent-light:   #E8F2F9;
  --color-accent-hover:   #155A87;
  --color-risk:           #C0392B;
  --color-safe:           #27AE60;

  /* Type scale */
  --text-xs:   0.75rem;
  --text-sm:   0.875rem;
  --text-base: 1.0625rem;
  --text-lg:   1.25rem;
  --text-xl:   1.5rem;
  --text-2xl:  2rem;
  --text-3xl:  2.75rem;
  --text-hero: 3.5rem;

  /* Layout */
  --width-content: 860px;
  --width-wide:    1100px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: var(--text-base);
  color: var(--color-text-primary);
  background: var(--color-bg);
  line-height: 1.75;
}

img {
  display: block;
  max-width: 100%;
}

code,
pre {
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
}

/* ─── Skip link ───────────────────────────────────────────── */

.skip-link {
  position: absolute;
  left: -9999px;
  top: auto;
  width: 1px;
  height: 1px;
  overflow: hidden;
}

.skip-link:focus {
  position: fixed;
  top: 0;
  left: 0;
  width: auto;
  height: auto;
  padding: 0.5rem 1rem;
  background: var(--color-accent);
  color: #fff;
  font-family: "DM Sans", sans-serif;
  font-size: var(--text-sm);
  z-index: 9999;
  overflow: visible;
}

/* ─── Sticky nav ──────────────────────────────────────────── */

.sticky-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 48px;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 200ms ease;
}

.sticky-nav.is-visible {
  opacity: 1;
  pointer-events: auto;
}

.sticky-nav__inner {
  display: flex;
  gap: 2rem;
  align-items: center;
}

.nav-link {
  font-family: "DM Sans", sans-serif;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 2px solid transparent;
  transition: color 150ms ease, border-color 150ms ease;
}

.nav-link:hover {
  color: var(--color-text-primary);
  border-bottom-color: var(--color-border);
}

.nav-link.is-active {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.nav-link:focus-visible {
  outline: 2px solid var(--color-text-primary);
  outline-offset: 2px;
}

/* ─── Hero ────────────────────────────────────────────────── */

.hero {
  background: var(--color-bg);
  text-align: center;
  padding: 120px 24px 100px;
}

.hero__inner {
  max-width: var(--width-content);
  margin: 0 auto;
}

.hero__badge {
  display: inline-block;
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.06em;
  padding: 4px 14px;
  border-radius: 100px;
  margin-bottom: 20px;
}

.hero__title {
  margin: 0 auto 0;
  font-family: "Libre Baskerville", Georgia, serif;
  font-weight: 700;
  font-size: var(--text-hero);
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
  max-width: 820px;
}

.hero__authors {
  margin: 28px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 16px;
  font-weight: 400;
  color: var(--color-text-primary);
}

.hero__affiliations {
  margin: 8px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 14px;
  color: var(--color-text-secondary);
}

.hero__emails {
  margin: 6px 0 0;
  font-family: "JetBrains Mono", monospace;
  font-size: 13px;
  color: var(--color-text-muted);
}

.dot {
  margin: 0 4px;
  opacity: 0.6;
}

.hero__buttons {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 36px;
}

.hero-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  border-radius: 6px;
  font-family: "DM Sans", sans-serif;
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  transition: background 150ms ease, color 150ms ease, border-color 150ms ease;
}

.hero-btn--filled {
  background: var(--color-text-primary);
  color: #fff;
  border: 1.5px solid var(--color-text-primary);
}

.hero-btn--filled:hover,
.hero-btn--filled:focus-visible {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
}

.hero-btn--outline {
  background: transparent;
  color: var(--color-text-primary);
  border: 1.5px solid var(--color-border);
}

.hero-btn--outline:hover,
.hero-btn--outline:focus-visible {
  border-color: var(--color-text-primary);
}

.hero-btn--venue:hover,
.hero-btn--venue:focus-visible {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.venue-logo {
  height: 14px;
  width: auto;
  display: inline-block;
  vertical-align: middle;
}

.hero-btn:focus-visible {
  outline: 2px solid var(--color-text-primary);
  outline-offset: 2px;
}

.hero__tldr {
  margin-top: 40px;
}

.hero__rule {
  border: none;
  border-top: 1px solid var(--color-border);
  max-width: 320px;
  margin: 24px auto;
}

.hero__tldr-label {
  margin: 0 0 8px;
  font-family: "DM Sans", sans-serif;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.hero__tldr-body {
  margin: 0 auto;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: 18px;
  font-style: italic;
  color: var(--color-text-secondary);
  max-width: 640px;
  line-height: 1.65;
}

/* ─── Section rule ────────────────────────────────────────── */

.section-rule {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 0;
}

/* ─── Page shell ──────────────────────────────────────────── */

.page-shell {
  width: min(calc(100% - 2rem), var(--width-content));
  margin: 0 auto;
  padding: 0 0 5rem;
}

/* ─── Abstract section ────────────────────────────────────── */

.abstract-section {
  padding: 80px 24px;
  text-align: center;
}

.abstract__eyebrow {
  margin: 0 0 24px;
  font-family: "DM Sans", sans-serif;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.abstract__body {
  margin: 0 auto;
  max-width: 72ch;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: var(--text-base);
  line-height: 1.75;
  color: var(--color-text-primary);
  text-align: left;
}

/* ─── Content sections ────────────────────────────────────── */

.content-section {
  padding: 64px 0;
  border-top: 1px solid var(--color-border);
}

.content-section:first-child {
  border-top: none;
  padding-top: 80px;
}

.content-section h2 {
  margin: 0 0 1rem;
  font-family: "Libre Baskerville", Georgia, serif;
  font-weight: 700;
  font-size: var(--text-2xl);
  letter-spacing: -0.01em;
  color: var(--color-text-primary);
}

.content-section h3 {
  margin: 0 0 0.5rem;
  font-family: "Libre Baskerville", Georgia, serif;
  font-weight: 600;
  font-size: var(--text-xl);
  color: var(--color-text-primary);
}

.content-section p {
  margin: 0.85rem 0 0;
  max-width: 72ch;
}

/* ─── Figures ─────────────────────────────────────────────── */

.figure-card {
  margin: 1.5rem 0 0;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

.figure-card img {
  width: 100%;
  background: var(--color-surface);
}

.figure-card figcaption {
  padding: 0.875rem 1rem 1rem;
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
  line-height: 1.6;
  border-top: 1px solid var(--color-border);
}

/* ─── Results grid ────────────────────────────────────────── */

.results-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 1.25rem;
}

.result-card {
  padding: 1.25rem;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
}

.result-card h3 {
  margin: 0;
  font-size: var(--text-base);
}

.result-card p {
  margin-top: 0.5rem;
  color: var(--color-text-secondary);
  font-size: var(--text-sm);
}

/* ─── Main content sections ──────────────────────────────── */

.main-section {
  padding: 96px 0;
}

.main-section h2 {
  margin: 0 0 24px;
  font-family: "Libre Baskerville", Georgia, serif;
  font-weight: 700;
  font-size: var(--text-2xl);
  letter-spacing: -0.01em;
  color: var(--color-text-primary);
}

.section-prose {
  margin: 0;
  max-width: 72ch;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: var(--text-base);
  line-height: 1.75;
  color: var(--color-text-primary);
}

/* ─── SOTA comparison table ───────────────────────────────── */

.sota-wrap {
  max-width: 780px;
  margin: 40px auto 0;
  overflow-x: auto;
}

.sota-table {
  width: 100%;
  border-collapse: collapse;
  font-family: "DM Sans", sans-serif;
  font-size: 15px;
}

.sota-th {
  padding: 14px 20px;
  font-weight: 600;
  border-bottom: 1px solid var(--color-border);
}

.sota-th--method {
  text-align: left;
}

.sota-th--criteria {
  text-align: center;
}

.sota-td {
  padding: 14px 20px;
  border-bottom: 1px solid var(--color-border);
}

.sota-td--method {
  font-weight: 500;
  text-align: left;
}

.sota-td--icon {
  text-align: center;
  white-space: nowrap;
}

.sota-examples {
  display: block;
  font-size: 13px;
  font-weight: 400;
  color: var(--color-text-secondary);
  margin-top: 2px;
}

.sota-icon {
  display: inline-block;
  vertical-align: middle;
}

.sota-icon--check {
  color: var(--color-safe);
}

.sota-icon--cross {
  color: var(--color-risk);
}

.sota-partial {
  font-style: italic;
  color: var(--color-text-secondary);
}

.sota-row-ramac {
  background: var(--color-accent-light);
  font-weight: 600;
}

.sota-td--ramac {
  color: var(--color-accent);
}

.sota-ours {
  font-weight: 400;
  color: var(--color-text-secondary);
}

.sota-caption {
  margin: 16px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  text-align: center;
  color: var(--color-text-secondary);
}

/* ─── Paper figure ────────────────────────────────────────── */

.paper-figure {
  max-width: 820px;
  margin: 40px auto 0;
}

.paper-figure__img {
  width: 100%;
  border: 1px solid var(--color-border);
  border-radius: 8px;
}

.paper-figure__caption {
  margin: 12px 0 0;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: var(--text-sm);
  font-style: italic;
  color: var(--color-text-secondary);
  line-height: 1.6;
  text-align: center;
}

/* ─── Equation block ──────────────────────────────────────── */

.eq-block {
  background: var(--color-surface);
  border-left: 3px solid var(--color-accent);
  padding: 24px 32px;
  border-radius: 0 8px 8px 0;
  max-width: 640px;
  margin: 32px auto 0;
  overflow-x: auto;
}

.eq-caption {
  margin: 16px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  font-style: italic;
  color: var(--color-text-secondary);
  line-height: 1.55;
}

/* ─── Figure placeholder ──────────────────────────────────── */

.figure-placeholder {
  border: 2px dashed var(--color-border);
  border-radius: 8px;
  height: 280px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
  font-family: "DM Sans", sans-serif;
  font-size: 14px;
  margin: 40px auto 0;
  max-width: 820px;
}

/* ─── Scroll-reveal ───────────────────────────────────────── */

.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ─── Subsection headings (H3) ───────────────────────────── */

.main-section h3,
.subsection-heading {
  margin: 64px 0 16px;
  font-family: "Libre Baskerville", Georgia, serif;
  font-weight: 600;
  font-size: var(--text-xl);
  color: var(--color-text-primary);
  letter-spacing: -0.01em;
}

/* ─── Table shared utilities ──────────────────────────────── */

.table-caption {
  margin: 16px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  font-style: italic;
  text-align: center;
  color: var(--color-text-secondary);
  line-height: 1.55;
}

.table-footnote {
  margin: 8px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  text-align: center;
  color: var(--color-text-muted);
}

/* ─── Results table (Table 1) ─────────────────────────────── */

.results-wrap {
  max-width: var(--width-wide);
  margin: 32px auto 0;
  overflow-x: auto;
}

.results-table {
  width: 100%;
  border-collapse: collapse;
  font-family: "DM Sans", sans-serif;
  font-size: 14px;
}

.rt-th {
  padding: 11px 16px;
  font-weight: 600;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  white-space: nowrap;
}

.rt-th--left {
  text-align: left;
}

.rt-th--metric {
  text-align: left;
  font-weight: 500;
  color: var(--color-text-secondary);
}

.rt-th--num {
  text-align: right;
}

.rt-th--radac {
  color: var(--color-accent);
  font-weight: 700;
}

.rt-td {
  padding: 11px 16px;
  border-bottom: 1px solid var(--color-border);
}

.rt-td--dataset {
  font-weight: 500;
  white-space: nowrap;
  vertical-align: middle;
}

.rt-td--metric {
  font-size: 13px;
  color: var(--color-text-secondary);
}

.rt-td--num {
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.rt-td--best {
  font-weight: 700;
  color: var(--color-accent);
}

.rt-td--second {
  background: var(--color-accent-light);
}

/* ─── Table 2 (OOD action rate) ───────────────────────────── */

.table2-wrap {
  max-width: 520px;
  margin: 24px auto 0;
  overflow-x: auto;
}

.table2 {
  width: 100%;
  border-collapse: collapse;
  font-family: "DM Sans", sans-serif;
  font-size: 14px;
}

/* ─── Theory section ─────────────────────────────────────── */

.theory-eyebrow {
  margin: 0 0 12px;
  font-family: "DM Sans", sans-serif;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.prop1-box {
  border: 2px solid var(--color-accent);
  border-radius: 8px;
  background: var(--color-accent-light);
  padding: 28px 32px;
  max-width: 700px;
  margin: 40px auto 0;
}

.prop1-label {
  margin: 0 0 16px;
  font-family: "DM Sans", sans-serif;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent);
}

.prop1-body {
  margin: 0;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text-primary);
}

.prop1-interp {
  margin: 16px 0 0;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

/* ─── Citation ────────────────────────────────────────────── */

.bibtex-wrap {
  position: relative;
  max-width: 720px;
  margin: 24px auto 0;
}

.bibtex-block {
  margin: 0;
  padding: 24px 28px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 8px;
  overflow-x: auto;
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  font-size: 14px;
  line-height: 1.65;
  color: var(--color-text-primary);
}

.bibtex-block code {
  font-family: inherit;
  font-size: inherit;
}

.bibtex-copy-btn {
  position: absolute;
  top: 12px;
  right: 12px;
  padding: 4px 10px;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  color: var(--color-accent);
  cursor: pointer;
  transition: border-color 150ms ease, background 150ms ease;
}

.bibtex-copy-btn:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent);
}

.bibtex-copy-btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.bibtex-live-region {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

/* ─── Site footer ─────────────────────────────────────────── */

.site-footer {
  padding: 0 0 48px;
}

.footer-text {
  margin: 16px 0 0;
  font-family: "DM Sans", sans-serif;
  font-size: 13px;
  color: var(--color-text-muted);
  text-align: center;
}

.section-note {
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  margin-top: 1rem;
}

/* ─── Responsive ──────────────────────────────────────────── */

@media (max-width: 639px) {
  .sticky-nav {
    display: none;
  }

  .main-section {
    padding: 64px 0;
  }

  .hero {
    padding: 80px 24px 64px;
  }

  .hero__title {
    font-size: var(--text-3xl);
  }

  .hero__affiliations {
    display: flex;
    flex-direction: column;
    gap: 4px;
  }

  .hero__affiliations .dot {
    display: none;
  }

  .page-shell {
    padding-bottom: 4rem;
  }

  .results-grid {
    grid-template-columns: 1fr;
  }

  .content-section {
    padding: 48px 0;
  }
}

@media (max-width: 479px) {
  .hero__buttons {
    flex-direction: column;
    align-items: stretch;
  }

  .hero-btn {
    justify-content: center;
  }

  .sticky-nav__inner {
    gap: 1rem;
    overflow-x: auto;
    padding: 0 1rem;
  }
}

/* ─── prefers-reduced-motion ──────────────────────────────── */

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

  .reveal {
    opacity: 1;
    transform: none;
  }
}