/* =========================================================
   DPI Health Hackathon 2026 — Stylesheet
   Pure black/white brand system. Bold sans-serif.
   ========================================================= */

:root {
  --black: #000000;
  --white: #ffffff;
  --grey-50: #fafafa;
  --grey-100: #f2f2f2;
  --grey-200: #e5e5e5;
  --grey-400: #999999;
  --grey-600: #555555;
  --grey-800: #1a1a1a;
  --max: 1200px;
  --radius: 0px; /* sharp, editorial */
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
}

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

html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }

body {
  font-family: var(--font);
  color: var(--black);
  background: var(--white);
  line-height: 1.55;
  font-size: 17px;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

/* ---------- Layout ---------- */
.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 32px;
}

section { padding: 96px 0; }
section.tight { padding: 64px 0; }

/* ---------- Nav (inverted: black background, white text) ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--black);
  color: var(--white);
  border-bottom: 1px solid #222;
}
.nav a { color: var(--white); }
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 32px;
  max-width: var(--max);
  margin: 0 auto;
}
.nav-logo {
  font-weight: 900;
  font-size: 17px;
  letter-spacing: 0.02em;
  display: flex;
  align-items: center;
  gap: 14px;
  text-transform: uppercase;
}
.nav-wordmark {
  font-weight: 900;
  font-size: 17px;
  letter-spacing: 0.04em;
  color: var(--white);
  text-transform: uppercase;
  white-space: nowrap;
}
.nav-links {
  display: flex;
  gap: 32px;
  align-items: center;
  font-size: 15px;
  font-weight: 500;
}
.nav-links a:hover { opacity: 0.6; }
.nav-cta {
  background: var(--white);
  color: var(--black) !important;
  padding: 10px 20px;
  font-weight: 600;
}
.nav-cta:hover { opacity: 0.85 !important; }
.nav-toggle { display: none; background: none; border: none; font-size: 24px; cursor: pointer; color: var(--white); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 18px 36px;
  font-weight: 700;
  font-size: 16px;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  border: 2px solid var(--black);
  cursor: pointer;
  transition: all 0.2s ease;
}
.btn-primary { background: var(--black); color: var(--white); }
.btn-primary:hover { background: var(--white); color: var(--black); }
.btn-outline { background: transparent; color: var(--black); }
.btn-outline:hover { background: var(--black); color: var(--white); }
.btn-light { background: var(--white); color: var(--black); border-color: var(--white); }
.btn-light:hover { background: transparent; color: var(--white); border-color: var(--white); }

/* ---------- Headings ---------- */
h1, h2, h3, h4 { font-weight: 900; letter-spacing: -0.02em; line-height: 1.05; }
h1 { font-size: clamp(44px, 7vw, 96px); }
h2 { font-size: clamp(32px, 4.5vw, 56px); margin-bottom: 32px; }
h3 { font-size: 22px; font-weight: 800; margin-bottom: 12px; }
h4 { font-size: 16px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 16px; }

.eyebrow {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  border: 1px solid var(--black);
  padding: 8px 16px;
  margin-bottom: 24px;
}

.lead { font-size: 20px; color: var(--grey-600); max-width: 720px; margin-bottom: 32px; }

/* ---------- Hero ---------- */
.hero {
  padding: 120px 0 96px;
  border-bottom: 1px solid var(--grey-200);
}
.hero h1 { margin-bottom: 32px; }
.hero-meta {
  display: flex;
  gap: 40px;
  flex-wrap: wrap;
  margin: 40px 0 48px;
  padding: 24px 0;
  border-top: 1px solid var(--grey-200);
  border-bottom: 1px solid var(--grey-200);
}
.hero-meta > div { min-width: 140px; }
.hero-meta .label { font-size: 12px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em; color: var(--grey-400); margin-bottom: 6px; }
.hero-meta .value { font-size: 20px; font-weight: 800; }
.hero-cta { display: flex; gap: 16px; flex-wrap: wrap; align-items: center; }
.hero-note { font-size: 14px; color: var(--grey-600); }

/* ---------- Section headers ---------- */
.section-head { margin-bottom: 56px; max-width: 760px; }
.section-head .lead { font-size: 18px; margin-bottom: 0; }

/* ---------- Grids ---------- */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 32px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 32px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }

/* ---------- Cards ---------- */
.card {
  border: 1px solid var(--black);
  padding: 32px;
  transition: transform 0.2s ease, background 0.2s ease, color 0.2s ease;
}
.card:hover { background: var(--black); color: var(--white); transform: translateY(-4px); }
.card-num {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  color: var(--grey-400);
  margin-bottom: 16px;
  letter-spacing: 0.1em;
}
.card h3 { margin-bottom: 12px; }
.card p { font-size: 15px; line-height: 1.6; }

/* ---------- Focus areas (icon grid) ---------- */
.lanes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; border: 1px solid var(--black); }
.lane {
  padding: 40px 32px;
  border-right: 1px solid var(--black);
  border-bottom: 1px solid var(--black);
}
.lane:nth-child(3n) { border-right: none; }
.lane:nth-last-child(-n+3) { border-bottom: none; }
.lane-icon { font-size: 28px; margin-bottom: 20px; display: block; }
.lane h3 { font-size: 19px; margin-bottom: 10px; }
.lane p { font-size: 14px; color: var(--grey-600); line-height: 1.55; }

/* ---------- Prize row ---------- */
.prizes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; border: 2px solid var(--black); }
.prize {
  padding: 48px 32px;
  text-align: center;
  border-right: 2px solid var(--black);
}
.prize:last-child { border-right: none; }
.prize .place { font-size: 13px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.15em; color: var(--grey-600); margin-bottom: 12px; }
.prize .amount { font-size: 44px; font-weight: 900; letter-spacing: -0.02em; }
.prize.top { background: var(--black); color: var(--white); }
.prize.top .place { color: #999; }

/* ---------- Timeline ---------- */
.timeline { border-top: 1px solid var(--black); }
.tl-item {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 40px;
  padding: 32px 0;
  border-bottom: 1px solid var(--grey-200);
}
.tl-date { font-size: 14px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; }
.tl-content h3 { font-size: 20px; margin-bottom: 8px; }
.tl-content p { color: var(--grey-600); font-size: 15px; }

/* ---------- FAQ ---------- */
.faq details {
  border-bottom: 1px solid var(--grey-200);
  padding: 24px 0;
}
.faq summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 19px;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-size: 28px; font-weight: 300; }
.faq details[open] summary::after { content: "−"; }
.faq details p { margin-top: 16px; color: var(--grey-600); font-size: 16px; line-height: 1.65; }

/* ---------- Big CTA band ---------- */
.cta-band {
  background: var(--black);
  color: var(--white);
  padding: 120px 0;
  text-align: center;
}
.cta-band h2 { margin-bottom: 24px; }
.cta-band p { color: #aaa; max-width: 600px; margin: 0 auto 40px; font-size: 19px; }

/* ---------- Footer ---------- */
footer {
  background: var(--black);
  color: var(--white);
  padding: 72px 0 32px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 48px;
  margin-bottom: 56px;
}
footer h4 { color: var(--white); margin-bottom: 20px; font-size: 13px; }
footer ul { list-style: none; }
footer ul li { margin-bottom: 10px; }
footer a { color: #aaa; font-size: 14px; }
footer a:hover { color: var(--white); }
.footer-brand { font-weight: 900; font-size: 24px; letter-spacing: 0.02em; margin-bottom: 12px; text-transform: uppercase; }
.footer-tag { color: #aaa; font-size: 14px; max-width: 320px; line-height: 1.6; }
.footer-info { color: #aaa; font-size: 14px; }
.footer-info li { margin-bottom: 10px; }
.footer-bottom {
  border-top: 1px solid #222;
  padding-top: 32px;
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  color: #666;
  flex-wrap: wrap;
  gap: 16px;
}

/* ---------- Two-column narrative ---------- */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center; }
.split-img { aspect-ratio: 4/5; background: var(--grey-100); }

/* ---------- Mini list ---------- */
.checklist { list-style: none; }
.checklist li {
  padding: 16px 0 16px 36px;
  position: relative;
  border-bottom: 1px solid var(--grey-200);
  font-size: 16px;
}
.checklist li::before {
  content: "→";
  position: absolute;
  left: 0;
  top: 16px;
  font-weight: 900;
}

/* ---------- Expandable Tracks ---------- */
.tracks {
  border: 1px solid var(--black);
  background: var(--white);
}
.track {
  border-bottom: 1px solid var(--black);
}
.track:last-child { border-bottom: none; }
.track summary {
  cursor: pointer;
  list-style: none;
  display: grid;
  grid-template-columns: 48px 1fr 32px;
  align-items: center;
  gap: 20px;
  padding: 28px 32px;
  transition: background 0.15s ease, color 0.15s ease;
}
.track summary::-webkit-details-marker { display: none; }
.track summary:hover { background: var(--black); color: var(--white); }
.track summary:hover .track-sub { color: #bbb; }
.track summary:hover .track-toggle { color: var(--white); }
.track-icon {
  font-size: 26px;
  line-height: 1;
  display: inline-block;
}
.track-head { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.track-title {
  font-size: 22px;
  font-weight: 800;
  letter-spacing: -0.01em;
}
.track-sub {
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--grey-600);
}
.track-toggle {
  font-size: 28px;
  font-weight: 300;
  text-align: right;
  transition: transform 0.2s ease;
}
.track[open] > summary {
  background: var(--black);
  color: var(--white);
}
.track[open] > summary .track-sub { color: #bbb; }
.track[open] > summary .track-toggle { color: var(--white); transform: rotate(45deg); }
.track-body {
  padding: 32px;
  border-top: 1px solid var(--grey-200);
  background: var(--white);
}
.track-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-bottom: 32px;
}
.track-body h4 {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--grey-400);
  margin-bottom: 10px;
}
.track-body p {
  font-size: 15px;
  color: var(--grey-600);
  line-height: 1.6;
}
.mini-list { list-style: none; }
.mini-list li {
  font-size: 15px;
  color: var(--grey-600);
  padding: 6px 0 6px 18px;
  position: relative;
  line-height: 1.55;
}
.mini-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  top: 6px;
  color: var(--black);
  font-weight: 900;
}
.track-cta {
  display: inline-block;
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  border-bottom: 2px solid var(--black);
  padding-bottom: 2px;
}
.track-cta:hover { opacity: 0.65; }

/* ---------- Judges panel ---------- */
.judges {
  margin-top: 72px;
  padding-top: 56px;
  border-top: 1px solid var(--grey-200);
}
.judges-title {
  font-size: 28px;
  font-weight: 900;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}
.judges-lead {
  font-size: 17px;
  color: var(--grey-600);
  max-width: 680px;
  margin-bottom: 40px;
}
.judges-grid { gap: 0; border: 1px solid var(--black); }
.judge {
  padding: 32px 28px;
  border-right: 1px solid var(--black);
}
.judge:last-child { border-right: none; }
.judge-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  background: var(--black);
  color: var(--white);
  padding: 4px 10px;
  margin-bottom: 16px;
}
.judge h4 {
  font-size: 18px;
  font-weight: 800;
  text-transform: none;
  letter-spacing: -0.01em;
  margin-bottom: 8px;
}
.judge p {
  font-size: 14px;
  color: var(--grey-600);
  line-height: 1.55;
}

/* ---------- How-to-apply flow ---------- */
.flow {
  list-style: none;
  border-top: 2px solid var(--black);
  border-bottom: 2px solid var(--black);
}
.flow-step {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 32px;
  padding: 36px 0;
  border-bottom: 1px solid var(--grey-200);
  align-items: start;
}
.flow-step:last-child { border-bottom: none; }
.flow-num {
  font-size: 56px;
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1;
  color: var(--black);
}
.flow-step h3 {
  font-size: 22px;
  font-weight: 800;
  margin-bottom: 8px;
}
.flow-step p {
  font-size: 16px;
  color: var(--grey-600);
  line-height: 1.6;
  max-width: 720px;
}

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .grid-2, .grid-3, .grid-4, .lanes, .split, .footer-grid { grid-template-columns: 1fr !important; }
  .lane { border-right: none !important; border-bottom: 1px solid var(--black) !important; }
  .lane:last-child { border-bottom: none !important; }
  .prizes { grid-template-columns: 1fr; }
  .prize { border-right: none; border-bottom: 2px solid var(--black); }
  .prize:last-child { border-bottom: none; }
  .tl-item { grid-template-columns: 1fr; gap: 8px; }
  .nav-links { display: none; position: absolute; top: 100%; left: 0; right: 0; background: var(--black); flex-direction: column; padding: 24px 32px; border-bottom: 1px solid #222; gap: 20px; }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; }
  section { padding: 64px 0; }
  .hero { padding: 72px 0; }
  .nav-wordmark { font-size: 13px; letter-spacing: 0.02em; }

  /* Expandable tracks */
  .track summary { grid-template-columns: 36px 1fr 24px; gap: 14px; padding: 22px 20px; }
  .track-icon { font-size: 22px; }
  .track-title { font-size: 18px; }
  .track-sub { font-size: 11px; }
  .track-body { padding: 24px 20px; }
  .track-grid { grid-template-columns: 1fr; gap: 24px; }

  /* Judges */
  .judges-grid { grid-template-columns: 1fr !important; }
  .judge { border-right: none; border-bottom: 1px solid var(--black); }
  .judge:last-child { border-bottom: none; }

  /* How-to-apply flow */
  .flow-step { grid-template-columns: 1fr; gap: 8px; padding: 28px 0; }
  .flow-num { font-size: 40px; }
}