/* ── Tokens ─────────────────────────────────────────────────────── */
:root {
  --paper:      #FCFCFA;
  --ink:        #16181D;
  --muted:      #5A6270;
  --iris:       #4A44B2;   /* single accent: iris indigo */
  --iris-dark:  #37327F;
  --iris-tint:  #F3F2FA;
  --rule:       #E5E4EC;
  --serif: "IBM Plex Serif", Georgia, serif;
  --sans:  "IBM Plex Sans", -apple-system, "Segoe UI", sans-serif;
  --mono:  "IBM Plex Mono", "SF Mono", Menlo, monospace;
  --col: 880px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; scroll-padding-top: 4.5rem; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  background: var(--paper);
  color: var(--ink);
  font: 400 1rem/1.65 var(--sans);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--iris); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 2px; }
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--iris);
  outline-offset: 2px;
  border-radius: 2px;
}

/* ── Skip link ──────────────────────────────────────────────────── */
.skip-link {
  position: absolute;
  left: -9999px;
}
.skip-link:focus {
  position: fixed;
  left: 1rem;
  top: 1rem;
  z-index: 100;
  background: var(--iris);
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 6px;
}

/* ── Top navigation ─────────────────────────────────────────────── */
.topnav {
  border-bottom: 1px solid var(--rule);
  background: var(--paper);
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(6px);
  position: sticky;
  top: 0;
  z-index: 10;
}
.nav-inner {
  max-width: var(--col);
  margin: 0 auto;
  padding: 0.65rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.wordmark {
  font: 500 0.9rem var(--mono);
  letter-spacing: 0.04em;
  color: var(--ink);
}
.wordmark:hover { text-decoration: none; color: var(--iris); }
.nav-links {
  display: flex;
  align-items: center;
  gap: 1.1rem;
  flex-wrap: wrap;
  font-size: 0.88rem;
}
.nav-links a { color: var(--muted); }
.nav-links a:hover { color: var(--iris); text-decoration: none; }
.nav-cta {
  color: var(--iris) !important;
  border: 1px solid var(--iris);
  border-radius: 999px;
  padding: 0.2rem 0.75rem;
}
.nav-cta:hover { background: var(--iris-tint); }

/* ── Layout ─────────────────────────────────────────────────────── */
main {
  max-width: var(--col);
  margin: 0 auto;
  padding: 0 1.25rem 4rem;
}
section { margin-top: 3.5rem; }
section > p { max-width: 72ch; margin-bottom: 0.9rem; }
section > p:last-child { margin-bottom: 0; }

h2 {
  font: 600 1.4rem/1.3 var(--serif);
  margin-bottom: 0.9rem;
  padding-top: 0.9rem;
  border-top: 2px solid var(--ink);
  display: inline-block;
  padding-right: 2.5rem;
}

/* ── Hero ───────────────────────────────────────────────────────── */
.hero { padding-top: 3rem; text-align: center; }
.venue {
  font: 500 0.78rem var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--iris);
  margin-bottom: 1rem;
}
h1 {
  font: 600 clamp(1.75rem, 4.5vw, 2.5rem)/1.2 var(--serif);
  letter-spacing: -0.01em;
  max-width: 24em;
  margin: 0 auto 1.3rem;
}
.authors {
  font-size: 1.02rem;
  max-width: 40em;
  margin: 0 auto 0.35rem;
}
.authors sup { font-size: 0.7em; color: var(--muted); }
.affiliations {
  color: var(--muted);
  font-size: 0.92rem;
  margin-bottom: 1.8rem;
}
.affiliations sup { font-size: 0.75em; }

.button-row {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 2rem;
}
.btn {
  display: inline-block;
  font: 500 0.9rem var(--sans);
  color: var(--ink);
  border: 1px solid var(--rule);
  border-radius: 6px;
  padding: 0.42rem 1rem;
  background: #fff;
  transition: border-color 120ms ease, background 120ms ease;
}
.btn:hover { text-decoration: none; border-color: var(--iris); color: var(--iris); }
.btn-primary {
  background: var(--iris);
  border-color: var(--iris);
  color: #fff;
}
.btn-primary:hover { background: var(--iris-dark); border-color: var(--iris-dark); color: #fff; }

.stats {
  list-style: none;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.4rem 0;
  font: 400 0.82rem var(--mono);
  color: var(--muted);
}
.stats li { padding: 0 0.9rem; }
.stats li + li { border-left: 1px solid var(--rule); }
.stats b { color: var(--ink); font-weight: 500; }

/* ── Teaser ─────────────────────────────────────────────────────── */
.teaser { margin-top: 2.2rem; }
.teaser img {
  width: 100%;
  height: auto;
  border-radius: 8px;
  border: 1px solid var(--rule);
}
figcaption {
  font-size: 0.85rem;
  color: var(--muted);
  margin-top: 0.6rem;
  text-align: center;
}

/* ── Dataset modalities ─────────────────────────────────────────── */
.modality-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.7rem;
  margin: 1.4rem 0;
}
.modality {
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 0.8rem 1rem;
  background: #fff;
}
.mod-name {
  display: block;
  font: 500 0.82rem var(--mono);
  color: var(--iris);
  margin-bottom: 0.15rem;
}
.mod-spec { font-size: 0.92rem; color: var(--ink); }

/* ── Examples ───────────────────────────────────────────────────── */
.example-row {
  display: grid;
  grid-template-columns: 6.2rem 1fr;
  gap: 1rem;
  align-items: center;
  margin-top: 1.4rem;
}
.emotion-tag {
  font: 500 0.82rem var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--iris);
}
.example-videos {
  display: grid;
  grid-template-columns: minmax(0, 2.1fr) minmax(0, 1fr) minmax(0, 1fr);
  gap: 0.7rem;
  align-items: center;
}
.example-videos video {
  width: 100%;
  height: auto;
  border-radius: 6px;
  background: #000;
  display: block;
}

.video-toggle {
  margin-top: 0.2rem;
  font-size: 0.82rem;
  cursor: pointer;
}

/* ── Access (signature section) ─────────────────────────────────── */
#access {
  background: var(--iris-tint);
  border: 1px solid color-mix(in srgb, var(--iris) 22%, transparent);
  border-radius: 12px;
  padding: 2rem 2.2rem 2.2rem;
}
#access h2 { border-top-color: var(--iris); }

.access-steps {
  list-style: none;
  counter-reset: step;
  margin-top: 1.6rem;
}
.access-steps li {
  counter-increment: step;
  position: relative;
  padding: 0 0 1.7rem 3.4rem;
}
.access-steps li:last-child { padding-bottom: 0; }
/* numbered rail */
.access-steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: -0.2rem;
  width: 2.1rem;
  height: 2.1rem;
  border-radius: 50%;
  background: var(--iris);
  color: #fff;
  font: 500 1rem var(--mono);
  display: flex;
  align-items: center;
  justify-content: center;
}
.access-steps li::after {
  content: "";
  position: absolute;
  left: calc(1.05rem - 1px);
  top: 2.2rem;
  bottom: 0.3rem;
  width: 2px;
  background: color-mix(in srgb, var(--iris) 30%, transparent);
}
.access-steps li:last-child::after { display: none; }

.access-steps h3 {
  font: 600 1.05rem/1.35 var(--sans);
  margin-bottom: 0.25rem;
}
.access-steps p {
  color: var(--muted);
  max-width: 58ch;
  margin-bottom: 0.7rem;
}
.access-steps li:last-child p { margin-bottom: 0; }

.access-note {
  margin-top: 1.8rem;
  border-top: 1px solid color-mix(in srgb, var(--iris) 25%, transparent);
  padding-top: 1.1rem;
  font-size: 0.92rem;
  color: var(--muted);
  max-width: 68ch;
}
.access-note b { color: var(--ink); }

/* ── BibTeX ─────────────────────────────────────────────────────── */
.bibtex-wrap { position: relative; }
.bibtex-wrap pre {
  background: #F6F6F3;
  border: 1px solid var(--rule);
  border-radius: 8px;
  padding: 1.1rem 1.2rem;
  overflow-x: auto;
  font: 400 0.8rem/1.55 var(--mono);
}
.copy-btn {
  position: absolute;
  top: 0.6rem;
  right: 0.6rem;
  font: 500 0.78rem var(--sans);
  color: var(--muted);
  background: #fff;
  border: 1px solid var(--rule);
  border-radius: 5px;
  padding: 0.25rem 0.7rem;
  cursor: pointer;
}
.copy-btn:hover { color: var(--iris); border-color: var(--iris); }

/* ── Contact / footer ───────────────────────────────────────────── */
.contact-list { list-style: none; }
.contact-list li { margin-bottom: 0.35rem; }
.email { font: 400 0.9rem var(--mono); color: var(--muted); }

footer {
  border-top: 1px solid var(--rule);
  margin-top: 4rem;
  padding: 1.5rem 1.25rem 2rem;
  text-align: center;
  font: 400 0.8rem var(--mono);
  color: var(--muted);
}

/* ── Responsive ─────────────────────────────────────────────────── */
@media (max-width: 720px) {
  .modality-grid { grid-template-columns: 1fr; }
  .example-row { grid-template-columns: 1fr; gap: 0.5rem; }
  #access { padding: 1.5rem 1.2rem 1.6rem; }
  /* keep the sticky bar one row tall: wordmark + Request access only */
  .nav-links a:not(.nav-cta) { display: none; }
  .nav-inner { gap: 0.5rem; }
  .wordmark { font-size: 0.78rem; }
}
@media (max-width: 480px) {
  .example-videos { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
  .example-videos .v-world { grid-column: 1 / -1; }
}