/* ============================================================
   Grain overlay (sits above bg, below content)
   ============================================================ */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image: var(--grain-url);
  opacity: 0.55;
  mix-blend-mode: overlay;
}
body > * { position: relative; z-index: 1; }

/* ============================================================
   Top scroll progress bar (Apple-style, hair-thin)
   ============================================================ */
.scroll-bar {
  position: fixed;
  top: 0; left: 0;
  height: 1.5px;
  width: 0%;
  background: var(--accent);
  z-index: 200;
  pointer-events: none;
  transition: width 60ms linear;
}

/* ============================================================
   Top navigation (v3 — plain text, no pill)
   ============================================================ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  transition: background 200ms var(--ease), border-color 200ms var(--ease);
  background: transparent;
  border-bottom: 1px solid transparent;
}

.nav.is-scrolled {
  background: rgba(15, 15, 17, 0.78);
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  border-bottom-color: var(--border);
}

.nav__inner {
  width: 100%;
  max-width: var(--container-w);
  margin-inline: auto;
  padding-inline: var(--container-pad);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-5);
}

.nav__brand {
  font-family: var(--mono);
  font-size: 15px;
  letter-spacing: 0.18em;
  font-weight: 500;
  text-transform: uppercase;
  color: var(--text);
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
}

/* Stylised mars dot icon — concentric ring + filled disc */
.nav__brand-icon {
  width: 18px; height: 18px;
  display: inline-block;
  margin-right: var(--s-1);
  position: relative;
}
.nav__brand-icon::before,
.nav__brand-icon::after {
  content: "";
  position: absolute;
  inset: 0; margin: auto;
  border-radius: 50%;
}
.nav__brand-icon::before {
  width: 16px; height: 16px;
  border: 1px solid var(--accent);
  opacity: 0.6;
}
.nav__brand-icon::after {
  width: 7px; height: 7px;
  background: var(--accent);
  box-shadow: 0 0 12px var(--accent);
}

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--s-6);
}

.nav__link, .nav__cta {
  font-family: var(--mono);
  font-size: 14px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-soft);
  padding: 4px 0;
  border-bottom: 1px solid transparent;
  transition: color var(--d-fast) var(--ease), border-color var(--d-fast) var(--ease);
}

.nav__link:hover { color: var(--text); border-bottom-color: var(--text-muted); }
.nav__link.is-active { color: var(--text); border-bottom-color: var(--accent); }

.nav__cta { color: var(--accent); margin-left: var(--s-4); }
.nav__cta:hover { color: var(--text); border-bottom-color: var(--accent); }

@media (max-width: 720px) {
  .nav__links { gap: var(--s-3); }
  .nav__link { display: none; }
  .nav__cta { display: inline-block; }
}

/* ============================================================
   Hero (v3 — no marquee, content-first)
   ============================================================ */
.hero {
  position: relative;
  width: 100%;
  isolation: isolate;
  overflow: hidden;
}

.hero__media {
  position: absolute;
  inset: 0;
  z-index: -1;
  overflow: hidden;
}

.hero__media video,
.hero__media img {
  width: 100%; height: 100%;
  object-fit: cover;
  opacity: 0.62;
}

.hero__media::after {
  content: "";
  position: absolute;
  inset: 0;
  /* center scrim keeps the title/authors legible; edges stay bright so the
     video grid reads clear and sharp (Generalist-style) instead of hazy */
  background:
    radial-gradient(ellipse 80% 66% at 50% 44%,
      rgba(15,15,17,0.60) 0%,
      rgba(15,15,17,0.28) 56%,
      rgba(15,15,17,0.06) 100%),
    linear-gradient(to bottom,
      rgba(15,15,17,0.40) 0%,
      rgba(15,15,17,0.05) 20%,
      rgba(15,15,17,0.05) 78%,
      rgba(15,15,17,0.42) 100%);
}

/* Hero media — seamless 2×4 grid of 8 multimodal MARS clips */
.hero__media--grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 10px;
  background: var(--bg);
}

.hero__media--grid > video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.82;
  display: block;
  filter: contrast(1.04) saturate(1.02);
}

/* Mobile hero overrides live at the END of this hero section (after the base
   rules) so they win on source order — see the @media block further down. */

.hero__inner {
  text-align: center;
  padding-block: 18vh 12vh;
  max-width: 1100px;
  margin-inline: auto;
}

.hero__title {
  font-family: var(--display);
  font-weight: 600;
  font-size: var(--hero);
  line-height: 0.95;
  letter-spacing: 0.005em;
  margin-bottom: var(--s-4);
  color: var(--text-display);
  text-shadow: 0 4px 40px rgba(0, 0, 0, 0.55);
}

.hero__sub {
  font-family: var(--serif-display);
  font-style: italic;
  font-size: clamp(24px, 3vw, 40px);
  color: var(--text-display);
  line-height: 1.2;
  margin-bottom: var(--s-4);
  text-shadow: 0 2px 28px rgba(0, 0, 0, 0.7), 0 0 6px rgba(0, 0, 0, 0.4);
}

.hero__pitch {
  font-family: var(--serif-body);
  font-size: var(--text-lg);
  color: var(--text-display);
  max-width: 52ch;
  margin: 0 auto var(--s-7);
  letter-spacing: 0.005em;
  text-shadow: 0 2px 18px rgba(0, 0, 0, 0.7), 0 0 4px rgba(0, 0, 0, 0.4);
}

/* === A2A-style author block ============================================= */
.hero__authors {
  max-width: 1000px;
  margin: 0 auto var(--s-3);
  font-family: var(--serif-body);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--text-display);
  text-shadow: 0 1px 14px rgba(0, 0, 0, 0.65);
}

.hero__authors a {
  color: var(--text);
  border-bottom: 1px solid rgba(255, 255, 255, 0.18);
  transition: color var(--d-fast) var(--ease), border-color var(--d-fast) var(--ease);
}

.hero__authors a:hover {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.hero__authors sup {
  color: var(--accent);
  font-size: 0.8em;
  margin-left: 1px;
  font-weight: 600;
}

.hero__affil {
  font-family: var(--serif-body);
  font-style: italic;
  font-size: var(--text-base);
  color: rgba(244, 240, 232, 0.92);
  margin: 0 auto var(--s-2);
  text-shadow: 0 1px 12px rgba(0, 0, 0, 0.65);
}
.hero__affil a {
  color: inherit;
  border-bottom: 1px solid rgba(255, 255, 255, 0.22);
  transition: color var(--d-fast) var(--ease), border-color var(--d-fast) var(--ease);
}
.hero__affil a:hover { color: var(--accent); border-bottom-color: var(--accent); }

.hero__marks {
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wide);
  color: rgba(237, 234, 227, 0.6);
  margin: 0 auto var(--s-6);
  text-shadow: 0 1px 12px rgba(0, 0, 0, 0.65);
}

.hero__marks span { margin: 0 var(--s-3); white-space: nowrap; }
/* Project-lead mark is the native double-dagger ‡ (U+2021) — a real footnote glyph,
   so it shares the exact metrics / superscript baseline of * and †. No custom sizing. */
.hero__marks sup { color: var(--accent); margin-right: 2px; }

/* === Hero logos row (NTU + MARS Lab) ==================================== */
.hero__logos {
  display: inline-flex;
  align-items: center;
  gap: var(--s-7);
  margin: var(--s-6) auto 0;
  padding: var(--s-4) var(--s-6);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: var(--r-md);
  background: rgba(15, 15, 17, 0.5);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.hero__logo {
  display: inline-flex;
  align-items: center;
  gap: var(--s-3);
  color: var(--text);
}

.hero__logo img {
  height: 36px;
  width: auto;
  display: block;
  opacity: 0.92;
}

.hero__logo--text {
  font-family: var(--serif);
  font-size: var(--text-lg);
  letter-spacing: 0.02em;
  line-height: 1;
  color: var(--text);
}

.hero__logo--text .ntu-mark {
  font-family: var(--mono);
  font-size: 22px;
  font-weight: 600;
  letter-spacing: 0.04em;
  padding: 4px 10px;
  border: 1.5px solid var(--accent-warm);
  border-radius: var(--r-sm);
  margin-right: var(--s-3);
  color: var(--text);
}

.hero__logo--text .ntu-name {
  font-family: var(--serif);
  font-size: var(--text-base);
  letter-spacing: 0.005em;
  color: var(--text);
  display: block;
  line-height: 1.2;
}

.hero__logo--text .ntu-sub {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-muted);
  display: block;
  margin-top: 2px;
}

.hero__logo--text {
  display: inline-flex;
  align-items: center;
}

.hero__logo-divider {
  width: 1px;
  height: 36px;
  background: rgba(255, 255, 255, 0.18);
}

.hero__cta-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--s-3);
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
  padding: var(--s-3) var(--s-5);
  font-family: var(--sans);
  font-size: var(--text-sm);
  font-weight: 500;
  letter-spacing: 0.01em;
  border-radius: var(--r-full);
  border: 1px solid var(--border-strong);
  background: rgba(255,255,255,0.02);
  color: var(--text);
  transition: transform var(--d-fast) var(--ease),
              background var(--d-fast) var(--ease),
              border-color var(--d-fast) var(--ease),
              box-shadow var(--d-base) var(--ease);
}

.btn:hover {
  transform: translateY(-1px);
  background: rgba(255,255,255,0.06);
  border-color: var(--accent-line);
  box-shadow: 0 0 0 4px var(--accent-soft);
}

.btn--primary {
  background: var(--text);
  color: var(--bg);
  border-color: transparent;
}

.btn--primary:hover {
  background: #fff;
  box-shadow: 0 0 0 4px var(--accent-soft);
}

.btn__icon {
  width: 14px; height: 14px;
  display: inline-block;
  stroke: currentColor;
  fill: none;
  stroke-width: 1.5;
}

@media (max-width: 720px) {
  /* Mobile hero — compact stacked layout. The video banner sits BELOW the nav
     (the desktop overlay let the transparent nav float over the bright clips), is
     trimmed to a tidy 2×2 of the four tasks so the title surfaces quickly, and is
     rounded into a contained card; title + content follow on the solid page bg.
     Placed AFTER the base hero rules so these overrides win on source order. */
  .section--hero { min-height: 0; display: block; padding-top: var(--nav-height); }
  .hero__media {
    position: relative; inset: auto; height: auto; z-index: 0;
    margin: var(--s-3) var(--s-4) 0;
    border-radius: var(--r-lg);
    overflow: hidden;
  }
  .hero__media::after { display: none; }
  .hero__media--grid {
    grid-template-columns: repeat(2, 1fr);
    grid-template-rows: none;
    gap: 4px;
  }
  .hero__media--grid > video { aspect-ratio: 16 / 9; height: auto; opacity: 0.95; }
  /* four tasks, one mode each — the mode-B clips are explored later in §02 */
  .hero__media--grid > video:nth-child(n + 5) { display: none; }
  .hero__inner { padding-block: var(--s-5) var(--s-7); }
  .hero__title { margin-top: var(--s-2); }
  .hero__authors { font-size: var(--text-sm); }
  .hero__affil,
  .hero__marks { font-size: var(--text-xs); }
  .hero__marks span { margin: 0 var(--s-2); }
}

/* ============================================================
   Chapter number (mono section header prefix)
   ============================================================ */
.chapter-num {
  display: inline-flex;
  align-items: center;
  gap: var(--s-3);
  font-family: var(--mono);
  font-size: 19px;
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: var(--accent-warm);
  margin-bottom: var(--s-5);
}

.chapter-num::after {
  content: "";
  display: block;
  width: 56px;
  height: 1px;
  background: rgba(217, 210, 192, 0.35);
}

/* ============================================================
   Section divider (v3 — every section starts with a hairline)
   ============================================================ */
.section--bordered {
  border-top: 1px solid var(--border);
}

/* ============================================================
   TL;DR strip (v2 — dual headline)
   ============================================================ */
.tldr {
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding-block: var(--s-10);
}

.tldr__line {
  font-family: var(--serif-display);
  font-size: clamp(32px, 4.4vw, 56px);
  line-height: 1.1;
  letter-spacing: var(--tracking-tight);
  color: var(--text-display);
  margin-bottom: var(--s-4);
  max-width: 26ch;
}

.tldr__line em { font-style: italic; color: var(--text-soft); }

.tldr__sub {
  font-family: var(--serif-body);
  font-style: italic;
  font-size: clamp(20px, 2.2vw, 28px);
  line-height: 1.4;
  color: var(--text-soft);
  margin-bottom: var(--s-9);
  max-width: 42ch;
  font-weight: 400;
}

.stats {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-5);
}

@media (min-width: 720px) {
  .stats { grid-template-columns: repeat(3, 1fr); }
}

.stat {
  padding-block: var(--s-4);
  border-top: 1px solid var(--border);
}

.stat__value {
  font-family: var(--sans);
  font-weight: 600;
  font-size: clamp(30px, 3.4vw, 46px);
  line-height: 1.05;
  letter-spacing: -0.01em;
  font-variant-numeric: lining-nums tabular-nums;
  color: var(--text-display);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  column-gap: 6px;
  row-gap: 2px;
}

.stat__value .unit {
  font-family: var(--sans);
  font-size: 0.46em;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0;
  white-space: nowrap;
}

.stat__label {
  margin-top: var(--s-3);
  font-family: var(--serif-body);
  font-size: var(--text-base);
  color: var(--text-muted);
  letter-spacing: 0.01em;
  line-height: 1.5;
}

/* ============================================================
   Section heading helper
   ============================================================ */
.section-title {
  font-family: var(--display-serif);
  font-weight: 500;
  font-size: clamp(30px, 3.6vw, 50px);
  line-height: 1.12;
  letter-spacing: -0.012em;
  margin-bottom: var(--s-7);
  max-width: 38ch;
  color: var(--text-display);
  text-wrap: balance;
}

.section-lead {
  font-family: var(--serif-body);
  font-size: var(--text-xl);
  color: var(--text-soft);
  line-height: var(--leading-snug);
  max-width: 54ch;
  margin-bottom: var(--s-8);
}

/* ============================================================
   Problem (two-col narrative)
   ============================================================ */
.dilemma {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-8);
}

@media (min-width: 720px) {
  .dilemma {
    grid-template-columns: 1fr 1px 1fr;
    align-items: center;
    column-gap: var(--s-9);
  }
  .dilemma__rule {
    background: var(--border);
    width: 1px; height: 60%;
    justify-self: center;
  }
}

.dilemma__rule { display: none; }
@media (min-width: 720px) { .dilemma__rule { display: block; } }

.dilemma__col h3 {
  font-family: var(--serif-display);
  font-weight: 400;
  font-size: clamp(22px, 2.3vw, 30px);
  line-height: 1.2;
  margin-bottom: var(--s-5);
  color: var(--text-display);
}

.dilemma__col p {
  font-family: var(--serif-body);
  color: var(--text-soft);
  max-width: 40ch;
  line-height: 1.6;
}

.dilemma__col--right { text-align: left; }
@media (min-width: 720px) {
  .dilemma__col--right { text-align: right; }
  .dilemma__col--right p { margin-left: auto; }
}

/* ============================================================
   Overview video — cinematic, centred player shown between the hero and § 01
   (title-card poster, native controls, click-to-play; faststart .mp4 streams
   on demand). The standalone section owns the top gap from the hero; § 01's
   own top padding provides the gap below.
   ============================================================ */
.overview-section { padding-block: var(--section-gap) 0; }
.overview-section .overview { margin-block: 0; }

.overview {
  max-width: 1080px;
  margin: var(--s-8) auto var(--s-9);
}

.overview__frame {
  position: relative;
  border-radius: var(--r-xl);
  overflow: hidden;
  background: #000;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.06),
    0 0 0 1px var(--border),
    0 40px 90px -42px rgba(0, 0, 0, 0.92);
  transition: box-shadow var(--d-base) var(--ease), transform var(--d-base) var(--ease);
}

.overview__frame:hover {
  transform: translateY(-2px);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.08),
    0 0 0 1px var(--border-strong),
    0 52px 110px -42px rgba(0, 0, 0, 0.95),
    0 0 70px -24px var(--accent-soft);
}

.overview__video {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #000;
}

@media (max-width: 720px) {
  .overview { margin: var(--s-6) auto var(--s-7); }
  .overview__frame { border-radius: var(--r-lg); }
}

/* ============================================================
   Insight (v8 — vertical stack: figure → centered quote → caption)
   ============================================================ */
.insight-stack {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-6);
}

.insight-stack .media-block { margin: 0; }
.insight-stack .media-block__chrome { padding: var(--s-3); }

.insight-narrative {
  max-width: 920px;
  margin: 0 auto;
  text-align: center;
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-4);
}

.insight-quote {
  font-family: var(--serif-display);
  font-size: clamp(36px, 5vw, 64px);
  line-height: 1.05;
  letter-spacing: var(--tracking-tight);
  color: var(--text-display);
  margin: 0 auto;
  max-width: 22ch;
}

.insight-quote em { font-style: italic; color: var(--accent); }

.insight-caption {
  font-family: var(--serif-body);
  font-size: var(--text-lg);
  color: var(--text-soft);
  line-height: 1.6;
  max-width: 60ch;
  margin: 0 auto;
}

.insight-caption strong { color: var(--text-display); font-weight: 500; }
.insight-caption .katex { color: var(--text); }

/* ============================================================
   Method
   ============================================================ */
.method-figure {
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: var(--s-5);
  background: var(--bg-elev);
}

.method-figure img { width: 100%; border-radius: var(--r-sm); }

.method-figure__caption {
  font-family: var(--serif-body);
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-top: var(--s-3);
  line-height: 1.55;
}

.steps { counter-reset: step; }

.steps__item {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--s-4);
  padding-block: var(--s-5);
  border-top: 1px solid var(--border);
}

.steps__item:last-child { border-bottom: 1px solid var(--border); }

.steps__item::before {
  counter-increment: step;
  content: counter(step, decimal-leading-zero);
  font-family: var(--mono);
  font-size: var(--text-sm);
  letter-spacing: var(--tracking-wider);
  color: var(--accent-warm);
  line-height: 1.8;
}

.steps__heading {
  font-family: var(--serif-display);
  font-size: var(--text-xl);
  font-weight: 400;
  line-height: 1.25;
  margin-bottom: var(--s-2);
  color: var(--text-display);
}

.steps__body {
  font-family: var(--serif-body);
  color: var(--text-soft);
  font-size: var(--text-base);
  line-height: 1.6;
}

.equation {
  display: block;
  margin-top: var(--s-4);
  padding: var(--s-4) var(--s-5);
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  overflow-x: auto;
}

.equation .katex { font-size: 1.05em; }

/* ============================================================
   MediaBlock — unified figure/video shell
   ============================================================ */
.media-block { margin: 0 0 var(--s-9); }

/* v9 — black figures bleed into the page (no card, no border).
   The figures already carry a pure-black background, so a transparent
   chrome makes them merge seamlessly with the page bg. */
.media-block__chrome {
  background: transparent;
  border: 0;
  border-radius: var(--r-md);
  overflow: hidden;
}

/* Videos still need a defined black frame to avoid a flash of page bg */
.media-block__chrome:has(.vp) {
  background: #000;
}

/* --card — keep the dark framed treatment for figures that are NOT
   black-background (e.g. white matplotlib appendix plots). */
.media-block--card .media-block__chrome {
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: var(--s-4);
  transition: border-color var(--d-base) var(--ease);
}
.media-block--card:hover .media-block__chrome { border-color: var(--border-strong); }

.media-block__chrome img,
.media-block__chrome > .vp,
.media-block__chrome > picture > img {
  width: 100%;
  display: block;
}

/* v11 — bleed figures carry their own alpha (unmultiply-from-black: alpha =
   per-pixel brightness, colour un-premultiplied). They composite normally and
   float on the page with no box and no edge fringe, on ANY page colour. No
   blend mode — mix-blend-mode would re-introduce the stacking-context trap
   that left a visible black rectangle on the warm bg. */

/* Benchmark split (FIG. 08) — three independent panels + one shared legend.
   Replaces the single tall stacked composite. */
/* 2×2 editorial grid:
   row 1 → (a) Push Cube | (b) Grasp Eyeglass
   row 2 → (c) Collision Avoidance | text + legend */
.bench-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--s-7) var(--s-6);
  align-items: center;
  margin: 0 0 var(--s-9);
}
.bench-cell { margin: 0; }
.bench-cell .media-block__chrome { max-width: none; margin: 0; }

.bench-text { align-self: center; padding-inline: var(--s-2); }
.bench-text .media-block__label { display: block; margin-bottom: var(--s-3); }
.bench-text .media-block__title { margin: 0 0 var(--s-4); }
.bench-text .media-block__caption { margin: 0; }
.bench-text .bench-legend { margin: var(--s-6) 0 0; }

.bench-legend { max-width: 360px; }
.bench-legend img { width: 100%; height: auto; display: block; }

@media (max-width: 760px) {
  .bench-grid { grid-template-columns: 1fr; gap: var(--s-7); }
  .bench-text { padding-inline: 0; }
}

/* Narrow / portrait figures shouldn't span full width */
.media-block--narrow .media-block__chrome {
  max-width: 660px;
  margin-inline: auto;
}

/* Constrained figures — FIG.03 real-world summary (a bit smaller),
   FIG.11 robustness (smaller still) */
.media-block--compact .media-block__chrome { max-width: 920px; margin-inline: auto; }
.media-block--xs .media-block__chrome { max-width: 480px; margin-inline: auto; }

.media-block__meta {
  margin-top: var(--s-4);
  display: grid;
  grid-template-columns: auto 1fr;
  column-gap: var(--s-4);
  row-gap: var(--s-2);
  align-items: center;
}

.media-block__label {
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--accent-warm);
  white-space: nowrap;
}

.media-block__rule {
  display: block;
  height: 1px;
  background: rgba(217, 210, 192, 0.25);
}

.media-block__title {
  grid-column: 1 / -1;
  font-family: var(--serif-display);
  font-weight: 400;
  font-size: clamp(20px, 2.2vw, 26px);
  line-height: 1.2;
  color: var(--text-display);
  margin: 0;
}

.media-block__caption {
  grid-column: 1 / -1;
  font-family: var(--serif-body);
  font-size: var(--text-base);
  color: var(--text-soft);
  line-height: 1.65;
  max-width: 70ch;
  margin: 0;
}

.media-block__caption strong { color: var(--accent-warm); font-weight: 500; }
.media-block__caption em { color: var(--accent-warm); font-style: normal; font-family: var(--mono); font-size: 0.88em; letter-spacing: 0.02em; }

/* ============================================================
   Real-World task cards (v8 — Mode A/B toggle per task)
   ============================================================ */
.task-card { position: relative; margin-bottom: var(--s-9); }

.task-card--mode-toggle .task-card__title {
  margin-bottom: var(--s-2);
}

/* Mode A/B toggle buttons (sit between description and video) */
.mode-tabs {
  display: inline-flex;
  gap: var(--s-2);
  margin-bottom: var(--s-5);
  padding: 4px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  flex-wrap: wrap;
}

.mode-tab {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  padding: var(--s-2) var(--s-4);
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--r-sm);
  cursor: pointer;
  transition: background var(--d-fast) var(--ease),
              border-color var(--d-fast) var(--ease),
              color var(--d-fast) var(--ease);
  text-align: left;
  min-width: 140px;
}

.mode-tab__label {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-muted);
}

.mode-tab__title {
  font-family: var(--serif-display);
  font-size: var(--text-lg);
  font-weight: 400;
  line-height: 1.1;
  color: var(--text-soft);
}

.mode-tab:hover {
  background: rgba(255, 255, 255, 0.03);
}

.mode-tab:hover .mode-tab__title { color: var(--text-display); }

.mode-tab.is-active {
  background: rgba(255, 107, 90, 0.10);
  border-color: var(--accent-line);
}

.mode-tab.is-active .mode-tab__label { color: var(--accent); }
.mode-tab.is-active .mode-tab__title { color: var(--text-display); }

.task-card__body { padding: var(--s-5) 0 0; }

.task-card__title {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s-4);
  margin-bottom: var(--s-2);
}

.task-card__title h3 {
  font-family: var(--serif-display);
  font-weight: 400;
  font-size: var(--text-2xl);
  line-height: 1.1;
  color: var(--text-display);
}

.task-card__title .kicker {
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-muted);
}

.task-card__desc {
  font-family: var(--serif-body);
  color: var(--text-soft);
  font-size: var(--text-base);
  line-height: 1.6;
  margin-bottom: var(--s-5);
  max-width: 64ch;
}

/* 3-column method comparison grid (MARS / FM / A2A side-by-side) */
.method-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-5);
  margin-top: var(--s-4);
}

@media (min-width: 720px) {
  .method-grid { grid-template-columns: repeat(3, 1fr); gap: var(--s-5); }
}

.method-col { display: flex; flex-direction: column; }

.method-col__chrome {
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  overflow: hidden;
}

.method-col__chrome .vp { aspect-ratio: 4 / 3; }

.method-col__name {
  margin-top: var(--s-3);
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-muted);
}

.method-col__name[data-method="MARS"] { color: var(--accent); }
.method-col__name .badge {
  display: inline-block;
  padding: 2px 6px;
  border: 1px solid currentColor;
  border-radius: var(--r-sm);
  font-size: 11px;
  margin-right: var(--s-2);
  vertical-align: 1px;
}

.method-col__verdict {
  margin-top: var(--s-1);
  font-family: var(--sans);
  font-size: var(--text-sm);
  color: var(--text-soft);
  line-height: 1.5;
}

/* ============================================================
   Ablations grid (v3 — no toggle, 3-row hierarchy)
   ============================================================ */
.ablations__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--s-7);
}

@media (min-width: 880px) {
  .ablations__grid { grid-template-columns: 1fr 1fr; gap: var(--s-7); }
  .ablations__grid .media-block--wide { grid-column: 1 / -1; }
}

/* ============================================================
   Real-World comparison tiles (§ 05) — compact, side-by-side
   ============================================================ */
.task { margin: 0 0 var(--s-9); }
.task__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s-6);
  margin-bottom: var(--s-5);
}
.task__name {
  font-family: var(--serif-display);
  font-weight: 400;
  font-size: clamp(22px, 2.4vw, 30px);
  line-height: 1.15;
  color: var(--text-display);
  margin: 0 0 var(--s-2);
}
/* Cormorant's hyphen sits high/tilted — render hyphens inside display headings
   with the sans glyph (flat) without touching the surrounding serif letters. */
.flat-hyphen { font-family: var(--sans); font-style: normal; }
.task__desc {
  color: var(--text-soft);
  font-size: var(--text-base);
  line-height: 1.55;
  margin: 0;
  max-width: 64ch;
}
.task__robot {
  flex: none;
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--accent-warm);
  white-space: nowrap;
}

.cmp { display: grid; gap: var(--s-5); }
.cmp--2 { grid-template-columns: repeat(2, 1fr); }
.cmp--3 { grid-template-columns: repeat(3, 1fr); }

.cmp__tile { margin: 0; }
.cmp__media {
  position: relative;
  aspect-ratio: 16 / 9;
  background: #000;
  border-radius: var(--r-md);
  overflow: hidden;
  box-shadow: 0 0 0 1px var(--border);
}
.cmp__tile--ours .cmp__media { box-shadow: 0 0 0 1.5px var(--accent-line); }
.cmp__media video { width: 100%; height: 100%; object-fit: cover; display: block; cursor: pointer; }

/* --- per-tile playback controls (progress + speed) --- */
.cmp__ctrl {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  display: grid;
  grid-template-columns: auto 1fr auto auto;
  align-items: center;
  gap: var(--s-3);
  padding: 10px var(--s-3) 9px;
  background: linear-gradient(to top, rgba(0,0,0,0.78), rgba(0,0,0,0));
  opacity: 0;
  transition: opacity var(--d-base) var(--ease);
  z-index: 2;
}
.cmp__media:hover .cmp__ctrl,
.cmp__media.is-scrubbing .cmp__ctrl,
.cmp__ctrl:focus-within { opacity: 1; }

.cmp__pp {
  width: 22px; height: 22px;
  display: grid; place-items: center;
  color: #fff; cursor: pointer; position: relative;
}
.cmp__pp::before {
  content: ""; width: 0; height: 0;
  border-left: 9px solid currentColor;
  border-top: 6px solid transparent; border-bottom: 6px solid transparent;
  transform: translateX(1px);
}
.cmp__media.is-playing .cmp__pp::before {
  border: 0; width: 7px; height: 11px;
  border-left: 3px solid currentColor; border-right: 3px solid currentColor;
  transform: none;
}

.cmp__scrub {
  position: relative; height: 16px;
  display: flex; align-items: center; cursor: pointer; outline: none;
}
.cmp__scrub::before {
  content: ""; position: absolute; left: 0; right: 0;
  height: 2px; border-radius: 2px; background: rgba(255,255,255,0.28);
}
.cmp__scrub-fill {
  position: absolute; left: 0; height: 2px; width: 0;
  border-radius: 2px; background: var(--accent); pointer-events: none;
}
.cmp__scrub-thumb {
  position: absolute; left: 0; top: 50%;
  width: 9px; height: 9px; border-radius: 50%;
  background: var(--accent); transform: translate(-50%, -50%);
  pointer-events: none; transition: width var(--d-fast), height var(--d-fast);
}
.cmp__scrub:hover .cmp__scrub-thumb, .cmp__media.is-scrubbing .cmp__scrub-thumb { width: 13px; height: 13px; }

.cmp__time {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.03em;
  color: rgba(255,255,255,0.82); white-space: nowrap;
}

.cmp__speed {
  font-family: var(--mono); font-size: 11px; font-weight: 500;
  letter-spacing: 0.04em; color: #fff; cursor: pointer;
  padding: 3px 8px; border-radius: var(--r-sm);
  border: 1px solid rgba(255,255,255,0.28);
  background: rgba(0,0,0,0.35);
  transition: border-color var(--d-fast) var(--ease), background var(--d-fast) var(--ease);
}
.cmp__speed:hover { border-color: var(--accent); background: rgba(0,0,0,0.6); }

.cmp__cap { display: flex; flex-direction: column; gap: 3px; margin-top: var(--s-3); }
.cmp__label {
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-soft);
  display: inline-flex;
  align-items: center;
  gap: var(--s-2);
}
.cmp__label--ours { color: var(--accent); }
.cmp__ours {
  font-size: 10px;
  letter-spacing: 0.04em;
  text-transform: lowercase;
  color: var(--accent);
  border: 1px solid var(--accent-line);
  border-radius: 999px;
  padding: 1px 7px;
}
.cmp__note { color: var(--text-muted); font-size: var(--text-base); line-height: 1.45; }

/* Mode picker — switch the MARS "ours" tile between its two sampled modes */
.mode-pick {
  display: inline-flex;
  gap: var(--s-1);
  width: max-content;
  margin: var(--s-2) 0 var(--s-1);
  padding: 3px;
  border: 1px solid var(--border);
  border-radius: var(--r-full);
  background: rgba(255, 255, 255, 0.02);
}
.mode-pick__btn {
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  color: var(--text-soft);
  padding: 4px 13px;
  border-radius: var(--r-full);
  transition: color var(--d-fast) var(--ease), background var(--d-fast) var(--ease);
}
.mode-pick__btn:hover { color: var(--text); }
.mode-pick__btn.is-active { background: var(--accent); color: #0A0A0A; }
/* Baseline (non-"ours") tiles get a neutral active state so coral stays MARS-only */
.cmp__tile:not(.cmp__tile--ours) .mode-pick__btn.is-active { background: var(--border-strong); color: var(--text-display); }

@media (max-width: 760px) {
  .task__head { flex-direction: column; gap: var(--s-2); }
  .cmp--2, .cmp--3 { grid-template-columns: 1fr; }
}

/* ============================================================
   VideoPlayer
   ============================================================ */
.vp {
  position: relative;
  aspect-ratio: 16 / 9;
  background: #000;
  overflow: hidden;
  isolation: isolate;
}

.vp__video {
  width: 100%; height: 100%;
  object-fit: cover;
  display: block;
}

.vp__overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  opacity: 0;
  transition: opacity var(--d-fast) var(--ease);
  pointer-events: none;
}

.vp:hover .vp__overlay,
.vp.is-paused .vp__overlay { opacity: 1; }

.vp__playpause {
  width: 64px; height: 64px;
  border-radius: 50%;
  background: rgba(15,15,17,0.6);
  border: 1px solid rgba(255,255,255,0.18);
  backdrop-filter: blur(8px);
  pointer-events: auto;
  position: relative;
  cursor: pointer;
}

.vp__playpause::before {
  content: "";
  position: absolute;
  inset: 0;
  margin: auto;
  width: 0; height: 0;
  border-left: 14px solid var(--text);
  border-top: 9px solid transparent;
  border-bottom: 9px solid transparent;
  transform: translateX(2px);
}

.vp.is-playing .vp__playpause::before {
  border: 0;
  width: 12px; height: 14px;
  border-left: 4px solid var(--text);
  border-right: 4px solid var(--text);
  transform: none;
}

.vp__controls {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  display: grid;
  grid-template-columns: auto 1fr auto auto;
  align-items: center;
  gap: var(--s-3);
  padding: var(--s-3) var(--s-4);
  background: linear-gradient(to top, rgba(0,0,0,0.62), rgba(0,0,0,0));
  opacity: 0;
  transform: translateY(8px);
  transition: opacity var(--d-base) var(--ease), transform var(--d-base) var(--ease);
  pointer-events: none;
}

.vp:hover .vp__controls,
.vp:focus-within .vp__controls,
.vp.is-scrubbing .vp__controls {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.vp__pp-mini {
  width: 28px; height: 28px;
  display: grid; place-items: center;
  color: var(--text);
  cursor: pointer;
  position: relative;
}

.vp__pp-mini::before {
  content: "";
  width: 0; height: 0;
  border-left: 9px solid currentColor;
  border-top: 6px solid transparent;
  border-bottom: 6px solid transparent;
  transform: translateX(1px);
}

.vp.is-playing .vp__pp-mini::before {
  border: 0;
  width: 8px; height: 10px;
  border-left: 3px solid currentColor;
  border-right: 3px solid currentColor;
  transform: none;
}

.vp__scrub {
  position: relative;
  height: 18px;
  display: flex;
  align-items: center;
  cursor: pointer;
  outline: none;
}

.vp__scrub::before {
  content: "";
  position: absolute;
  left: 0; right: 0;
  height: 1.5px;
  background: rgba(255,255,255,0.22);
  border-radius: 2px;
}

.vp__scrub-fill {
  position: absolute;
  left: 0;
  height: 1.5px;
  width: 0;
  background: var(--accent);
  border-radius: 2px;
  transition: width 80ms linear;
  pointer-events: none;
}

.vp.is-scrubbing .vp__scrub-fill { transition: none; }

.vp__scrub-thumb {
  position: absolute;
  left: 0;
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
  transform: translate(-50%, -50%);
  top: 50%;
  transition: transform var(--d-fast) var(--ease), width var(--d-fast) var(--ease), height var(--d-fast) var(--ease);
  pointer-events: none;
}

.vp__scrub:hover .vp__scrub-thumb,
.vp.is-scrubbing .vp__scrub-thumb {
  width: 14px; height: 14px;
}

.vp__scrub:focus-visible::before {
  outline: 2px solid var(--accent-line);
  outline-offset: 4px;
}

.vp__time {
  font-family: var(--mono);
  font-size: var(--text-xs);
  color: var(--text-soft);
  letter-spacing: 0.04em;
  min-width: 10ch;
  text-align: right;
}

.vp__speed {
  font-family: var(--mono);
  font-size: var(--text-xs);
  letter-spacing: var(--tracking-wide);
  padding: 4px 10px;
  border: 1px solid rgba(255,255,255,0.18);
  border-radius: var(--r-sm);
  color: var(--text);
  background: rgba(15,15,17,0.45);
  cursor: pointer;
  transition: background var(--d-fast) var(--ease), border-color var(--d-fast) var(--ease);
}

.vp__speed:hover { background: rgba(15,15,17,0.7); border-color: var(--accent-line); }
.vp__speed[data-active="true"] { color: var(--accent); border-color: var(--accent-line); }

@media (max-width: 720px) {
  .vp__controls {
    opacity: 1 !important;
    transform: none !important;
    pointer-events: auto !important;
  }
}

/* ============================================================
   BibTeX section (re-added in v4)
   ============================================================ */
.bib {
  position: relative;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  padding: var(--s-5) var(--s-6);
  overflow: hidden;
}

.bib pre {
  margin: 0;
  font-family: var(--mono);
  font-size: var(--text-sm);
  color: var(--text-soft);
  line-height: 1.6;
  overflow-x: auto;
}

.bib__copy {
  position: absolute;
  top: var(--s-3);
  right: var(--s-3);
  padding: var(--s-2) var(--s-3);
  font-size: var(--text-xs);
  font-family: var(--mono);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--text-muted);
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.02);
  border-radius: var(--r-sm);
  transition: all var(--d-fast) var(--ease);
}

.bib__copy:hover { color: var(--text); border-color: var(--border-strong); }
.bib__copy.is-copied { color: var(--accent); border-color: var(--accent-line); }

/* ============================================================
   Footer (v3 — slim)
   ============================================================ */
.footer {
  border-top: 1px solid var(--border);
  padding-block: var(--s-9) var(--s-7);
  color: var(--text-muted);
}

.footer__row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-5);
  margin-bottom: var(--s-7);
}

.footer__brand {
  font-family: var(--serif);
  font-size: var(--text-2xl);
  color: var(--text);
}

.footer__links {
  display: flex;
  gap: var(--s-5);
  font-size: var(--text-sm);
  font-family: var(--mono);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
}

.footer__links a:hover { color: var(--accent); }

.footer__legal {
  font-family: var(--serif-body);
  font-style: italic;
  font-size: var(--text-base);
  color: var(--text-muted);
  letter-spacing: 0.01em;
}

/* ============================================================
   Reveal animations (driven by IntersectionObserver in JS)
   ============================================================ */
[data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 700ms var(--ease), transform 700ms var(--ease);
  transition-delay: var(--reveal-delay, 0ms);
}

[data-reveal].is-in { opacity: 1; transform: translateY(0); }

[data-split] { display: inline-block; }
[data-split] .char {
  display: inline-block;
  opacity: 0;
  transform: translateY(0.4em);
  transition: opacity 600ms var(--ease), transform 600ms var(--ease);
  transition-delay: calc(var(--i, 0) * 18ms);
}

[data-split].is-in .char { opacity: 1; transform: translateY(0); }

@media (prefers-reduced-motion: reduce) {
  [data-reveal], [data-split] .char {
    opacity: 1 !important;
    transform: none !important;
    transition: none !important;
    animation: none !important;
  }
}