/* ==========================================================================
   QuantiPhy Challenge — NeurIPS 2026
   Editorial scientific-notebook aesthetic
   ========================================================================== */

:root {
  /* Palette — warm paper, ink, single persimmon accent */
  --paper:        #F6F1E7;
  --paper-deep:   #EDE6D3;
  --paper-tint:   #FAF6EC;
  --ink:          #0E0E10;
  --ink-soft:     #25231F;
  --ink-muted:    #6B655B;
  --ink-faint:    #9A9388;
  --hairline:     rgba(14, 14, 16, 0.22);
  --hairline-soft:rgba(14, 14, 16, 0.10);
  --accent:       #C24A1B;
  --accent-deep:  #8E3411;
  --accent-soft:  rgba(194, 74, 27, 0.10);
  --accent-tint:  rgba(194, 74, 27, 0.04);
  --signal:       #1D5D43;

  /* Typography */
  --font-display: 'Fraunces', 'Times New Roman', serif;
  --font-body:    'Newsreader', Georgia, serif;
  --font-mono:    'JetBrains Mono', 'SF Mono', ui-monospace, monospace;

  /* Layout */
  --max-w:        1240px;
  --max-w-prose:  62ch;
  --gutter:       clamp(1.25rem, 4vw, 3.5rem);
  --rule:         1px solid var(--hairline);
  --rule-soft:    1px solid var(--hairline-soft);

  /* Type scale */
  --tx-display:   clamp(2.75rem, 7.2vw, 5.75rem);
  --tx-h1:        clamp(2rem, 4.2vw, 3.25rem);
  --tx-h2:        clamp(1.6rem, 2.8vw, 2.25rem);
  --tx-h3:        clamp(1.15rem, 1.7vw, 1.4rem);
  --tx-body:      1.0625rem;
  --tx-small:     0.875rem;
  --tx-eyebrow:   0.74rem;

  /* Motion */
  --ease:         cubic-bezier(0.2, 0.7, 0.2, 1);
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, p, ul, ol, figure, blockquote { margin: 0; padding: 0; }
ul, ol { list-style: none; }
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; background: none; border: 0; color: inherit; }

/* ---------- Base ---------- */
body {
  font-family: var(--font-body);
  font-size: var(--tx-body);
  font-weight: 400;
  line-height: 1.55;
  color: var(--ink);
  background-color: var(--paper);
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "kern", "liga", "calt";
}

::selection { background: var(--accent); color: var(--paper); }

/* ---------- Reusable atoms ---------- */
.wrap {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--tx-eyebrow);
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
}

.eyebrow::before {
  content: "";
  width: 1.5rem;
  height: 1px;
  background: var(--ink-soft);
}

.section-num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  color: var(--accent);
  font-weight: 500;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 400;
  line-height: 1.04;
  letter-spacing: -0.015em;
  color: var(--ink);
  font-variation-settings: "opsz" 144, "SOFT" 30, "WONK" 0;
}

h2 {
  font-size: var(--tx-h1);
  letter-spacing: -0.022em;
}

h3 {
  font-size: var(--tx-h2);
  letter-spacing: -0.015em;
  font-variation-settings: "opsz" 72, "SOFT" 50;
}

h4 {
  font-size: var(--tx-h3);
  font-weight: 500;
  letter-spacing: -0.005em;
  font-variation-settings: "opsz" 36, "wght" 500;
}

p { max-width: var(--max-w-prose); }
p + p { margin-top: 1em; }

a.link {
  color: var(--accent);
  border-bottom: 1px solid currentColor;
  transition: color 200ms var(--ease);
}
a.link:hover { color: var(--accent-deep); }

code, pre, .mono {
  font-family: var(--font-mono);
  font-feature-settings: "calt" 0;
}

/* ---------- Side ruler (decorative scroll indicator) ---------- */
.ruler {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: 28px;
  pointer-events: none;
  z-index: 50;
  display: none;
}
@media (min-width: 1100px) {
  .ruler { display: block; }
}
.ruler::before {
  content: "";
  position: absolute;
  inset: 0;
  border-right: 1px solid var(--hairline);
  background-image: repeating-linear-gradient(
    to bottom,
    transparent 0,
    transparent 39px,
    var(--hairline-soft) 39px,
    var(--hairline-soft) 40px
  );
}
.ruler::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(
    to bottom,
    transparent 0,
    transparent 199px,
    var(--hairline) 199px,
    var(--hairline) 200px
  );
}
.ruler__progress {
  position: absolute;
  left: 0; right: -1px;
  top: 0;
  height: 0%;
  background: var(--accent);
  transition: height 80ms linear;
  width: 2px;
  margin-left: auto;
}

/* ---------- Nav ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 40;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: var(--rule);
}
.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  padding-block: 1rem;
}
.nav__brand {
  display: inline-flex;
  align-items: baseline;
  gap: 0.65rem;
  font-family: var(--font-display);
  font-weight: 500;
  font-size: 1.25rem;
  letter-spacing: -0.015em;
  font-variation-settings: "opsz" 36, "SOFT" 30, "WONK" 1;
}
.nav__brand .dot {
  width: 9px; height: 9px; border-radius: 50%;
  background: var(--accent);
  align-self: center;
  box-shadow: 0 0 0 4px var(--accent-soft);
}
.nav__brand small {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-left: 0.25rem;
}
.nav__list {
  display: none;
  gap: 1.75rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
@media (min-width: 900px) {
  .nav__list { display: flex; }
}
.nav__list a {
  color: var(--ink-soft);
  position: relative;
  padding-block: 0.4rem;
  transition: color 200ms var(--ease);
}
.nav__list a::after {
  content: "";
  position: absolute;
  left: 0; right: 100%; bottom: 0;
  height: 1px;
  background: var(--accent);
  transition: right 200ms var(--ease);
}
.nav__list a:hover { color: var(--accent); }
.nav__list a:hover::after { right: 0; }

.nav__cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.55rem 0.9rem;
  background: var(--ink);
  color: var(--paper);
  border-radius: 999px;
  transition: background 200ms var(--ease);
}
.nav__cta:hover { background: var(--accent); }

.nav__toggle {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  padding: 0.4rem 0.5rem;
}
.nav__toggle span {
  width: 22px; height: 1.5px; background: var(--ink);
}
@media (min-width: 900px) { .nav__toggle { display: none; } }

.nav__drawer {
  display: none;
  flex-direction: column;
  gap: 0.25rem;
  padding: 0.5rem var(--gutter) 1.25rem;
  border-top: var(--rule);
  font-family: var(--font-mono);
  font-size: 0.84rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.nav__drawer.open { display: flex; }
.nav__drawer a {
  padding: 0.6rem 0;
  border-bottom: var(--rule-soft);
  color: var(--ink-soft);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  padding-block: clamp(3rem, 8vw, 6.5rem) clamp(2.5rem, 5vw, 4rem);
  overflow: hidden;
}
.hero__meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 1.75rem;
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--ink);
  border-radius: 999px;
  color: var(--ink);
  font-weight: 500;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
}
.badge--accent {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}
.badge--link {
  border-color: var(--ink);
  color: var(--ink);
  background: transparent;
  transition: background 200ms var(--ease), color 200ms var(--ease), border-color 200ms var(--ease);
}
.badge--link:hover {
  background: var(--ink);
  color: var(--paper);
}
.badge--link .arrow {
  font-size: 0.85em;
  display: inline-block;
  transition: transform 200ms var(--ease);
}
.badge--link:hover .arrow { transform: translate(2px, -2px); }
.hero__title {
  font-size: clamp(2.75rem, 8.4vw, 7.25rem);
  font-weight: 350;
  font-variation-settings: "opsz" 144, "SOFT" 20, "WONK" 1;
  letter-spacing: -0.035em;
  line-height: 0.96;
  max-width: 18ch;
}
.hero__title em {
  font-style: italic;
  color: var(--accent);
  font-variation-settings: "opsz" 144, "SOFT" 100, "WONK" 1;
}
.hero__subtitle {
  margin-top: 1.75rem;
  font-family: var(--font-body);
  font-style: italic;
  font-size: clamp(1.15rem, 1.7vw, 1.5rem);
  line-height: 1.4;
  color: var(--ink-soft);
  max-width: 56ch;
  font-weight: 300;
}
.hero__subtitle .highlight {
  font-style: normal;
  font-weight: 500;
  color: var(--ink);
  background: linear-gradient(to top, var(--accent-soft) 32%, transparent 32%);
  padding: 0 0.1em;
}
.hero__body {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(2rem, 4vw, 3rem);
  margin-top: clamp(2.5rem, 5vw, 4rem);
  padding-top: clamp(2rem, 4vw, 3rem);
  border-top: var(--rule);
}
@media (min-width: 980px) {
  .hero__body {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    gap: clamp(2.5rem, 5vw, 5rem);
    align-items: start;
  }
}
.hero__lede {
  font-size: clamp(1.05rem, 1.5vw, 1.2rem);
  line-height: 1.5;
  color: var(--ink-soft);
  max-width: 44ch;
}
.hero__lede strong {
  background: linear-gradient(to top, var(--accent-soft) 38%, transparent 38%);
  font-weight: 500;
}
.hero__ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1.5rem;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.85rem 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  background: var(--ink);
  color: var(--paper);
  border-radius: 4px;
  transition: transform 200ms var(--ease), background 200ms var(--ease);
}
.btn:hover { background: var(--accent); transform: translateY(-1px); }
.btn--ghost {
  background: transparent;
  color: var(--ink);
  border: 1px solid var(--hairline);
}
.btn--ghost:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.btn .arrow { font-size: 1rem; line-height: 0; transform: translateY(-1px); }

/* Hero specimen panel */
.specimen {
  background: var(--paper-tint);
  border: 1px solid var(--hairline);
  padding: 1.5rem 1.75rem;
  position: relative;
  font-family: var(--font-mono);
}
.specimen__row {
  display: grid;
  grid-template-columns: 9rem 1fr 2.5rem;
  align-items: center;
  gap: 1rem;
  padding-block: 0.85rem;
  font-size: 0.82rem;
  border-bottom: var(--rule-soft);
}
.specimen__row:last-child { border-bottom: 0; }
.specimen__row .k { color: var(--ink-muted); letter-spacing: 0.06em; }
.specimen__row .v { color: var(--ink); justify-self: end; font-weight: 500; }
.specimen__row .bar {
  height: 4px; background: var(--paper-deep); border-radius: 2px; position: relative; overflow: hidden;
}
.specimen__row .bar::after {
  content: "";
  position: absolute;
  inset: 0 var(--rest, 60%) 0 0;
  background: var(--accent);
  border-radius: 2px;
}
.specimen__footnote {
  margin-top: 1rem;
  font-family: var(--font-body);
  font-style: italic;
  font-size: 0.85rem;
  color: var(--ink-muted);
}

/* Hero countdown */
.countdown {
  margin-top: 2.5rem;
  border-top: var(--rule);
  border-bottom: var(--rule);
  padding-block: 1rem;
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 1.25rem;
}
.countdown__label {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
}
.countdown__cells {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.5rem;
  max-width: 480px;
  justify-self: end;
}
.countdown__cell {
  text-align: center;
  font-family: var(--font-display);
  font-variation-settings: "opsz" 72, "SOFT" 0, "WONK" 1;
}
.countdown__cell .n {
  font-size: clamp(1.6rem, 3vw, 2.25rem);
  font-weight: 300;
  letter-spacing: -0.02em;
  line-height: 1;
  display: block;
  color: var(--ink);
}
.countdown__cell .u {
  display: block;
  margin-top: 0.35rem;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

/* ---------- Section common ---------- */
section {
  position: relative;
  padding-block: clamp(3.5rem, 7vw, 6rem);
  background-color: var(--paper);
  background-image: radial-gradient(circle at 1px 1px, rgba(14, 14, 16, 0.045) 1px, transparent 0);
  background-size: 28px 28px;
  transition: background-color 400ms var(--ease);
}
section + section { border-top: var(--rule-soft); }

/* Section variants — alternating tones + subtle ink/accent shifts */
.sec--paper {
  background-color: #F6F1E7;
  background-image: radial-gradient(circle at 1px 1px, rgba(14, 14, 16, 0.045) 1px, transparent 0);
  background-size: 28px 28px;
  color: #0E0E10;
}
.sec--tint {
  background-color: #FBF7EC;
  background-image: radial-gradient(circle at 1px 1px, rgba(14, 14, 16, 0.035) 1px, transparent 0);
  background-size: 28px 28px;
  color: #1E1A14;
}
.sec--tint .section-head__num { color: var(--accent-deep); }
.sec--tint .eyebrow { color: #6B6354; }

.sec--deep {
  background-color: #EEE6D2;
  background-image: radial-gradient(circle at 1px 1px, rgba(14, 14, 16, 0.06) 1px, transparent 0);
  background-size: 28px 28px;
  color: #15120D;
}
.sec--deep .section-head__num { color: var(--signal); }
.sec--deep .eyebrow { color: #5E574B; }
.sec--deep .specimen,
.sec--deep .eval-formula,
.sec--deep .axis-figure,
.sec--deep .track-card,
.sec--deep .prize {
  background: rgba(255, 253, 247, 0.55);
  border-color: rgba(14, 14, 16, 0.18);
}
.sec--deep .stat,
.sec--deep .stats,
.sec--deep .sponsor-grid,
.sec--deep .sponsor {
  border-color: rgba(14, 14, 16, 0.18);
}
.sec--deep .org__avatar {
  /* subtle inset tile — distinct from section bg without being a bright overlay */
  background: rgba(14, 14, 16, 0.045);
  border-color: rgba(14, 14, 16, 0.18);
}
.section-head {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-bottom: 2.5rem;
}
@media (min-width: 900px) {
  .section-head {
    grid-template-columns: 8rem 1fr;
    gap: 2.5rem;
    align-items: baseline;
  }
}
.section-head__num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.section-head__num::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--hairline);
  display: none;
}
.section-head h2 {
  font-weight: 350;
  font-variation-settings: "opsz" 96, "SOFT" 35, "WONK" 1;
}
.section-head__deck {
  margin-top: 1rem;
  font-size: 1.1rem;
  color: var(--ink-muted);
  max-width: 60ch;
  font-style: italic;
  font-family: var(--font-body);
}

/* ---------- Overview ---------- */
.overview-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
}
@media (min-width: 900px) {
  .overview-grid {
    grid-template-columns: 1.2fr 1fr;
    gap: 4rem;
  }
}
.overview-grid p { font-size: 1.1rem; line-height: 1.6; color: var(--ink-soft); }
.overview-grid p + p { margin-top: 1.2em; }
.dropcap::first-letter {
  font-family: var(--font-display);
  font-size: 4.5em;
  font-weight: 400;
  float: left;
  line-height: 0.85;
  padding: 0.05em 0.15em 0 0;
  color: var(--accent);
  font-variation-settings: "opsz" 144, "SOFT" 100, "WONK" 1;
}

.objectives {
  display: grid;
  gap: 0;
  border-top: var(--rule);
}
.objective {
  display: grid;
  grid-template-columns: 3rem 1fr;
  gap: 1.25rem;
  padding-block: 1.25rem;
  border-bottom: var(--rule);
  align-items: baseline;
}
.objective__num {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  letter-spacing: 0.06em;
}
.objective h4 {
  font-size: 1.05rem;
  margin-bottom: 0.25rem;
}
.objective p { color: var(--ink-muted); font-size: 0.98rem; max-width: none; }

/* ---------- Tracks ---------- */
.tracks {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}
@media (min-width: 900px) {
  .tracks { grid-template-columns: repeat(2, 1fr); }
}
.track-card {
  position: relative;
  background: var(--paper-tint);
  border: 1px solid var(--hairline);
  padding: 1.75rem 1.75rem 1.5rem;
  display: flex;
  flex-direction: column;
  transition: transform 280ms var(--ease), border-color 280ms var(--ease);
}
.track-card:hover {
  transform: translateY(-3px);
  border-color: var(--ink);
}
.track-card__head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  border-bottom: var(--rule);
  padding-bottom: 1rem;
  margin-bottom: 1.25rem;
}
.track-card__id {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
}
.track-card__chip {
  font-family: var(--font-mono);
  font-size: 0.66rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  padding: 0.3rem 0.6rem;
  border: 1px solid var(--hairline);
  border-radius: 999px;
  color: var(--ink-soft);
  white-space: nowrap;
}
.track-card--featured { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.track-card--featured .track-card__id,
.track-card--featured .track-card__chip { color: var(--paper); border-color: rgba(246,241,231,0.3); }
.track-card--featured h3 { color: var(--paper); }
.track-card--featured .track-card__desc { color: rgba(246,241,231,0.78); }
.track-card--featured .track-card__head { border-color: rgba(246,241,231,0.2); }
.track-card--featured .track-card__meta li { border-color: rgba(246,241,231,0.18); color: rgba(246,241,231,0.85); }
.track-card--featured .track-card__meta strong { color: var(--paper); }
.track-card--featured .track-card__link { color: var(--paper); }

.track-card h3 {
  font-size: 1.5rem;
  margin-bottom: 0.85rem;
  line-height: 1.05;
  font-variation-settings: "opsz" 72, "SOFT" 60, "WONK" 1;
}
.track-card__desc { color: var(--ink-soft); margin-bottom: 1.25rem; font-size: 0.98rem; }
.track-card__meta {
  display: grid;
  gap: 0;
  margin-top: auto;
  font-family: var(--font-mono);
  font-size: 0.78rem;
}
.track-card__meta li {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 0.55rem;
  border-top: 1px solid var(--hairline);
  color: var(--ink-muted);
}
.track-card__meta li:last-child { border-bottom: 1px solid var(--hairline); }
.track-card__meta strong {
  color: var(--ink);
  font-weight: 500;
  text-align: right;
}
.track-card__link {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  margin-top: 1.25rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  align-self: flex-start;
}
.track-card__link .arrow {
  transition: transform 200ms var(--ease);
}
.track-card:hover .track-card__link .arrow { transform: translateX(4px); }

/* ---------- Dataset ---------- */
.dataset {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
}
@media (min-width: 900px) {
  .dataset { grid-template-columns: 1fr 1fr; gap: 4rem; align-items: start; }
}
.stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0;
  border-top: var(--rule);
  border-left: var(--rule);
}
.stat {
  border-right: var(--rule);
  border-bottom: var(--rule);
  padding: 1.5rem 1.25rem 1.25rem;
}
.stat .v {
  display: block;
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 2.75rem);
  font-weight: 350;
  line-height: 1;
  letter-spacing: -0.02em;
  font-variation-settings: "opsz" 96, "SOFT" 10, "WONK" 1;
  color: var(--ink);
}
.stat .v sup {
  font-size: 0.4em;
  vertical-align: super;
  margin-left: 0.1em;
  color: var(--accent);
  font-weight: 400;
}
.stat .k {
  display: block;
  margin-top: 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

.sources {
  display: grid;
  gap: 0;
  margin-top: 2rem;
}
.source {
  display: grid;
  grid-template-columns: 1.25rem 1fr;
  gap: 1.25rem;
  padding-block: 1.1rem;
  border-bottom: var(--rule-soft);
  align-items: baseline;
}
.source:first-child { border-top: var(--rule-soft); }
.source__mark {
  width: 12px; height: 12px;
  border: 1px solid var(--ink);
  margin-top: 0.4rem;
}
.source--sim .source__mark { background: var(--accent); border-color: var(--accent); }
.source--lab .source__mark { background: var(--paper); }
.source--wild .source__mark {
  background: repeating-linear-gradient(45deg, var(--ink) 0 2px, var(--paper) 2px 5px);
}
.source h4 { font-family: var(--font-body); font-size: 1rem; font-weight: 500; margin-bottom: 0.25rem; }
.source p { color: var(--ink-muted); font-size: 0.94rem; max-width: none; }

/* Dataset axis diagram */
.axis-figure {
  border: 1px solid var(--hairline);
  background: var(--paper-tint);
  padding: 1.75rem;
  position: relative;
}
.axis {
  display: grid;
  grid-template-columns: auto 1fr 1fr;
  gap: 0;
}
.axis__corner, .axis__col, .axis__row {
  padding: 0.85rem;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
  text-transform: uppercase;
}
.axis__col, .axis__row { background: var(--paper-deep); }
.axis__corner { background: transparent; }
.axis__cell {
  padding: 1.25rem 1rem;
  border: 1px solid var(--hairline);
  background: var(--paper);
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  align-items: center;
  justify-content: center;
}
.axis__cell strong {
  font-family: var(--font-display);
  font-weight: 400;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  font-variation-settings: "opsz" 36, "SOFT" 60;
}
.axis__cell span {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink-muted);
}
.axis__cell--filled { background: var(--accent-soft); border-color: var(--accent); }

/* ---------- Evaluation ---------- */
.eval-grid {
  display: grid;
  gap: 2rem;
}
.eval-formula {
  border: 1px solid var(--hairline);
  padding: clamp(1.25rem, 2.5vw, 1.75rem);
  background: var(--paper-tint);
  font-family: var(--font-body);
  font-size: 1.05rem;
  display: grid;
  gap: 0.6rem;
  position: relative;
}
.eval-formula__lede,
.eval-formula__note {
  font-size: 1rem;
  color: var(--ink-muted);
  max-width: none;
  line-height: 1.6;
}
.eval-formula__note { font-size: 0.95rem; }
/* Tighter rhythm: equation immediately follows its lede, then breathes before the next prose */
.eval-formula__lede + .math--display { margin-top: -0.2rem; }
.math--display + .eval-formula__note { margin-top: 0.4rem; }

/* ---------- Math display equations ---------- */
/* Math italic for variables — STIX Two Math / Cambria Math when available,
   Newsreader italic otherwise. Real math fonts ship a dedicated math italic
   alphabet and correct Greek glyphs. */
.mvar {
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', 'Latin Modern Math', 'Newsreader', Georgia, serif;
  font-style: italic;
  font-weight: 400;
  font-feature-settings: "ss01";
  letter-spacing: 0;
  padding-inline: 0.04em;
}
.msub {
  font-size: 0.62em;
  vertical-align: -0.35em;
  margin-left: 0.04em;
  font-style: italic;
}

.math__inline {
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', 'Newsreader', Georgia, serif;
  font-size: 1.02em;
  white-space: nowrap;
}

.math--display {
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', 'Latin Modern Math', 'Newsreader', Georgia, serif;
  font-size: clamp(1.02rem, 1.35vw, 1.18rem);
  font-weight: 400;
  line-height: 1.3;
  color: var(--ink-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.2em;
  margin-block: 0.15rem;
  padding: 0.5rem 0.25rem;
  position: relative;
  overflow-x: auto;
}

.math__op { font-style: normal; padding-inline: 0.05em; }
.math__op--lt { padding-inline: 0.25em; }
.math__op-name {
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', 'Newsreader', Georgia, serif;
  font-style: normal;
  font-feature-settings: "smcp" 0;
  letter-spacing: 0.02em;
}
.math__rel {
  font-style: normal;
  margin-inline: 0.45em;
  font-weight: 400;
}
.math__rhs { display: inline-flex; align-items: center; }
.math__bar {
  font-style: normal;
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', Georgia, serif;
  padding-inline: 0.04em;
}
.math__bracket {
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', Georgia, serif;
  font-style: normal;
  padding-inline: 0.05em;
}

/* Stacked fraction (numerator / denominator with horizontal bar) */
.math__frac {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  vertical-align: middle;
  line-height: 1.05;
  margin-inline: 0.15em;
}
.math__num {
  padding: 0 0.45em 0.18em;
  border-bottom: 1.4px solid currentColor;
  display: inline-flex;
  align-items: center;
  white-space: nowrap;
}
.math__denom {
  padding: 0.18em 0.45em 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  white-space: nowrap;
}
.math__frac--inline {
  font-size: 0.95em;
  margin-inline: 0.3em;
}

/* Big operator (∑) with sub/super limits */
.math__bigop {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  line-height: 1;
  margin-inline: 0.2em;
  font-style: normal;
}
.math__bigop-glyph {
  font-size: 1.3em;
  line-height: 0.9;
  font-family: 'STIX Two Text', 'STIX Two Math', 'Cambria Math', 'Latin Modern Math', serif;
  font-weight: 300;
}
.math__bigop-sub,
.math__bigop-sup {
  font-size: 0.5em;
  font-style: italic;
  line-height: 1;
}
.math__bigop-sup { order: -1; margin-bottom: 0.12em; }
.math__bigop-sub { margin-top: 0.12em; }

/* Equation number (right-aligned tag — paper convention) */
.math__tag {
  position: absolute;
  right: 0.5rem;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-style: normal;
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  color: var(--ink-faint);
}

/* Slim fraction bar — visually quieter at smaller display sizes */
.math__num { border-bottom-width: 1px; padding-bottom: 0.12em; }
.math__denom { padding-top: 0.12em; }

/* Hide equation tag on narrow screens to avoid overlap */
@media (max-width: 640px) {
  .math__tag { display: none; }
  .math--display { font-size: 1rem; padding: 0.4rem 0.25rem; }
}

.metric-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  border-top: var(--rule);
}
.metric {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: baseline;
  gap: 1.5rem;
  padding-block: 1.4rem;
  border-bottom: var(--rule);
}
.metric__code {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.06em;
  font-weight: 500;
  color: var(--accent);
  min-width: 4.5rem;
}
.metric__body h4 {
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 500;
  margin-bottom: 0.25rem;
  letter-spacing: 0;
}
.metric__body p { font-size: 0.95rem; color: var(--ink-muted); max-width: 64ch; }
.metric__tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.3rem 0.55rem;
  border: 1px solid var(--hairline);
  border-radius: 999px;
  color: var(--ink-muted);
  white-space: nowrap;
}

.composite-note {
  margin-top: 1.5rem;
  padding: 1.25rem 1.5rem;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-body);
  font-size: 0.98rem;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1.25rem;
  align-items: center;
  border-radius: 4px;
}
.composite-note .icon {
  width: 2.25rem; height: 2.25rem;
  border: 1px solid var(--paper);
  border-radius: 50%;
  display: grid; place-items: center;
  font-family: var(--font-display);
  font-weight: 300;
  font-size: 1.15rem;
  font-style: italic;
  font-variation-settings: "opsz" 36, "SOFT" 100, "WONK" 1;
}

/* ---------- Timeline ---------- */
.timeline {
  border-top: var(--rule);
}
.timeline__row {
  display: grid;
  grid-template-columns: 12rem 1fr;
  gap: 2rem;
  padding-block: 1.5rem;
  border-bottom: var(--rule);
  align-items: baseline;
}
@media (max-width: 700px) {
  .timeline__row {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }
}
.timeline__date {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--ink-soft);
  letter-spacing: 0.04em;
  line-height: 1.5;
}
.timeline__body {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}
.timeline__phase {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 400;
  font-variation-settings: "opsz" 72, "SOFT" 50, "WONK" 1;
  letter-spacing: -0.01em;
  line-height: 1.15;
}
.timeline__desc {
  font-family: var(--font-body);
  font-size: 0.95rem;
  line-height: 1.55;
  color: var(--ink-muted);
  max-width: 68ch;
  margin: 0;
}
.timeline__row--current .timeline__date { color: var(--accent); font-weight: 500; }
.timeline__row--current .timeline__phase::before {
  content: "●";
  color: var(--accent);
  margin-right: 0.5rem;
  font-size: 0.7em;
  vertical-align: middle;
}
.timeline__note {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-muted);
  white-space: nowrap;
}

/* ---------- Rules & Starter ---------- */
.col-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
  font-weight: 500;
  margin-bottom: 1rem;
}

/* Inline code chip used inside rule-list (e.g., `.csv`) */
.rule-list code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--paper-deep);
  padding: 0.08em 0.4em;
  border-radius: 3px;
  color: var(--ink);
}

/* Rules subsection — sits below the Steps + Kit row */
.compete-rules {
  margin-top: clamp(2.5rem, 5vw, 3.5rem);
  padding-top: clamp(2rem, 4vw, 3rem);
  border-top: var(--rule-soft);
}
.two-col {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
}
@media (min-width: 900px) {
  .two-col { grid-template-columns: 1fr 1fr; gap: 4rem; }
}
.rule-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: var(--rule);
}
.rule-list li {
  position: relative;
  padding: 1rem 0 1rem 1.75rem;
  border-bottom: var(--rule);
  font-size: 0.98rem;
  line-height: 1.55;
  color: var(--ink-soft);
}
.rule-list li::before {
  content: "+";
  position: absolute;
  left: 0;
  top: 1rem;
  color: var(--accent);
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 0.9rem;
  line-height: 1.55;
}
.rule-list strong {
  color: var(--ink);
  font-weight: 500;
}

.kit-card {
  background: var(--ink);
  color: var(--paper);
  padding: 2rem;
  border-radius: 4px;
}
.kit-card h3 {
  color: var(--paper);
  font-size: 1.5rem;
  margin-bottom: 1rem;
  font-variation-settings: "opsz" 72, "SOFT" 60;
}
.kit-card p { color: rgba(246,241,231,0.75); margin-bottom: 1.5rem; }
.kit-list {
  display: grid;
  gap: 0;
  margin-bottom: 1.5rem;
}
.kit-list li {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 1rem;
  padding-block: 0.85rem;
  border-bottom: 1px solid rgba(246,241,231,0.18);
  font-family: var(--font-mono);
  font-size: 0.84rem;
  align-items: center;
}
.kit-list li:first-child { border-top: 1px solid rgba(246,241,231,0.18); }
.kit-list .num { color: rgba(246,241,231,0.5); }
.kit-list .name { color: var(--paper); }
.kit-list .ext { color: var(--accent); font-size: 0.74rem; letter-spacing: 0.1em; }
.kit-card .btn { background: var(--paper); color: var(--ink); }
.kit-card .btn:hover { background: var(--accent); color: var(--paper); }
.kit-card .btn--ghost { background: transparent; color: var(--paper); border-color: rgba(246,241,231,0.3); }
.kit-card .btn--ghost:hover { background: var(--paper); color: var(--ink); border-color: var(--paper); }

/* ---------- Prizes ---------- */
.prizes-wrap {
  position: relative;
  isolation: isolate;
}
.prizes--blurred {
  filter: blur(11px) saturate(0.85);
  -webkit-filter: blur(11px) saturate(0.85);
  pointer-events: none;
  user-select: none;
  transform: scale(1.02); /* expand slightly to hide blurred edges within the wrapper */
  transform-origin: center;
}
.prizes-overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  z-index: 2;
  padding: 1rem;
}
.prizes-notice {
  background: var(--paper);
  border: 1px solid var(--ink);
  border-radius: 6px;
  padding: 1.5rem 2.25rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  box-shadow: 0 18px 48px rgba(14, 14, 16, 0.18), 0 2px 6px rgba(14, 14, 16, 0.06);
  max-width: 90%;
}
.prizes-notice__eyebrow {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--accent);
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
}
.prizes-notice__eyebrow::before,
.prizes-notice__eyebrow::after {
  content: "";
  display: inline-block;
  width: 1.25rem;
  height: 1px;
  background: var(--accent);
}
.prizes-notice__title {
  font-family: var(--font-display);
  font-weight: 400;
  font-variation-settings: "opsz" 96, "SOFT" 60, "WONK" 1;
  font-size: clamp(1.4rem, 2.6vw, 1.95rem);
  letter-spacing: -0.015em;
  line-height: 1.1;
  color: var(--ink);
}

.prizes {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}
@media (min-width: 800px) { .prizes { grid-template-columns: repeat(3, 1fr); } }
.prize {
  padding: 2rem 1.5rem;
  border: 1px solid var(--hairline);
  background: var(--paper-tint);
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  position: relative;
  overflow: hidden;
}
.prize__rank {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-muted);
}
.prize__amount {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 5vw, 3.5rem);
  font-weight: 350;
  letter-spacing: -0.03em;
  line-height: 1;
  font-variation-settings: "opsz" 144, "SOFT" 20, "WONK" 1;
  color: var(--ink);
}
.prize__amount sup {
  font-size: 0.45em;
  vertical-align: top;
  margin-right: 0.05em;
  color: var(--accent);
}
.prize__detail {
  font-size: 0.92rem;
  color: var(--ink-muted);
  max-width: 28ch;
}
.prize--gold .prize__amount { color: var(--accent); }
.prize--note {
  grid-column: 1 / -1;
  background: transparent;
  border: none;
  padding-top: 1rem;
  font-style: italic;
  color: var(--ink-muted);
  font-size: 0.92rem;
}

/* ---------- Organizers ---------- */
.org-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 1.5rem;
}
.org {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.org__avatar {
  width: 100%;
  aspect-ratio: 1;
  background: var(--paper-deep);
  border: 1px solid var(--hairline);
  position: relative;
  overflow: hidden;
}
.org__avatar img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  display: block;
}
.org__name {
  font-family: var(--font-body);
  font-weight: 500;
  font-size: 1rem;
  margin-top: 0.4rem;
  color: var(--ink);
  transition: color 200ms var(--ease);
}
a.org__name:hover { color: var(--accent); }
a.org__avatar {
  cursor: pointer;
  display: block;
}
a.org__avatar img { transition: transform 320ms var(--ease); }
a.org__avatar:hover img { transform: scale(1.03); }
.org__affil {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
  text-transform: uppercase;
}

.org-section {
  /* nested <section> elements must not paint their own background —
     they should sit on top of their parent variant's bg */
  background: transparent;
  background-image: none;
  padding-block: 0;
}
.org-section + .org-section { margin-top: 2.5rem; padding-top: 2.5rem; border-top: var(--rule-soft); }
.org-section h3 {
  font-size: 1.25rem;
  margin-bottom: 1.5rem;
  font-family: var(--font-mono);
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

/* ---------- Sponsors ---------- */
.sponsor-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 0;
  border-top: var(--rule);
  border-left: var(--rule);
}
.sponsor {
  border-right: var(--rule);
  border-bottom: var(--rule);
  padding: 2rem 1.25rem;
  display: grid;
  place-items: center;
  min-height: 8rem;
  text-align: center;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 400;
  letter-spacing: -0.01em;
  color: var(--ink-muted);
  font-variation-settings: "opsz" 36, "SOFT" 30;
}
.sponsor--open {
  color: var(--ink-faint);
  font-style: italic;
}

/* ---------- FAQ ---------- */
.faq { border-top: var(--rule); }
.faq details {
  border-bottom: var(--rule);
  padding-block: 1.25rem;
}
.faq summary {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 1.5rem;
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 1.05rem;
  list-style: none;
  align-items: baseline;
  color: var(--ink);
  font-weight: 500;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::before {
  content: counter(faq, decimal-leading-zero);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-muted);
  letter-spacing: 0.1em;
}
.faq { counter-reset: faq; }
.faq details { counter-increment: faq; }
.faq summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1.5rem;
  color: var(--accent);
  font-weight: 300;
  transition: transform 200ms var(--ease);
}
.faq details[open] summary::after { content: "−"; }
.faq details p {
  grid-column: 2 / 3;
  margin-top: 0.85rem;
  margin-left: calc(0.78rem + 1.5rem);
  color: var(--ink-muted);
  font-size: 0.98rem;
  padding-right: 2.5rem;
}

/* ---------- Citation ---------- */
.citation {
  background: var(--ink);
  color: var(--paper);
  padding: 2rem;
  border-radius: 4px;
  position: relative;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  overflow-x: auto;
  line-height: 1.65;
}
.citation pre { color: var(--paper); }
.citation pre .k { color: var(--accent); }
.citation pre .s { color: rgba(246,241,231,0.85); }
.citation pre .v { color: var(--paper); }
.citation__copy {
  position: absolute;
  top: 1rem; right: 1rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.5rem 0.8rem;
  background: rgba(246,241,231,0.1);
  color: var(--paper);
  border: 1px solid rgba(246,241,231,0.2);
  border-radius: 999px;
  transition: background 200ms var(--ease);
}
.citation__copy:hover { background: var(--accent); border-color: var(--accent); }

/* ---------- Footer ---------- */
.footer {
  border-top: 2px solid var(--ink);
  padding-block: 3rem 2rem;
  background: var(--paper);
}
.footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}
@media (min-width: 800px) {
  .footer__grid { grid-template-columns: 2fr 1fr 1fr 1fr; }
}
.footer__brand {
  font-family: var(--font-display);
  font-size: 1.75rem;
  font-weight: 350;
  letter-spacing: -0.02em;
  font-variation-settings: "opsz" 72, "SOFT" 35, "WONK" 1;
}
.footer__brand small {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-top: 0.5rem;
}
.footer h5 {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin-bottom: 1rem;
  font-weight: 500;
}
.footer ul { display: grid; gap: 0.5rem; }
.footer a { color: var(--ink-soft); }
.footer a:hover { color: var(--accent); }
.footer__legal {
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: var(--rule);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  color: var(--ink-muted);
}

/* ---------- Reveal animations ---------- */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 700ms var(--ease), transform 700ms var(--ease);
}
.reveal.in {
  opacity: 1;
  transform: none;
}
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  *, ::before, ::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  html { scroll-behavior: auto; }
}

/* ---------- Focus ---------- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

/* Skip link */
.skip {
  position: absolute;
  left: -9999px;
  top: auto;
  background: var(--ink);
  color: var(--paper);
  padding: 0.75rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  z-index: 100;
}
.skip:focus { left: 1rem; top: 1rem; }