/* ==========================================================================
   SciAgentVerse @ WSDM 2027 — shared stylesheet
   Palette drawn from the hero image: deep navy, scientific blue, warm gold.
   ========================================================================== */

:root {
  --navy-900: #061a3a;
  --navy-800: #0a2550;
  --navy-700: #0f3470;
  --blue-600: #1a56b0;
  --blue-500: #2a6fd1;
  --blue-100: #e6eefa;
  --blue-50:  #f3f7fd;
  --gold-500: #c99a2e;
  --gold-100: #fbf3e0;

  --ink:      #17223b;
  --ink-soft: #46536b;
  --ink-mute: #6b778c;
  --line:     #dfe5ef;
  --bg:       #ffffff;
  --bg-alt:   #f5f8fc;

  --radius: 12px;
  --shadow-sm: 0 1px 2px rgba(10, 37, 80, .06), 0 1px 3px rgba(10, 37, 80, .08);
  --shadow-md: 0 6px 24px rgba(10, 37, 80, .10);

  --serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --maxw: 1120px;
  --nav-h: 64px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-h) + 16px); }
body {
  margin: 0;
  font-family: var(--sans);
  font-size: 16.5px;
  line-height: 1.65;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: var(--blue-600); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3 { font-family: var(--serif); color: var(--navy-800); line-height: 1.25; margin: 0 0 .5em; }
p { margin: 0 0 1em; }

.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

/* ---------- Navigation ---------- */
.site-nav {
  position: sticky; top: 0; z-index: 50;
  height: var(--nav-h);
  background: rgba(6, 26, 58, .96);
  backdrop-filter: saturate(140%) blur(8px);
  border-bottom: 1px solid rgba(255, 255, 255, .08);
}
.site-nav .container { height: 100%; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: flex; align-items: baseline; gap: 10px; color: #fff; font-weight: 700; letter-spacing: .01em; }
.brand:hover { text-decoration: none; }
.brand .name { font-family: var(--serif); font-size: 20px; }
.brand .venue { font-size: 12.5px; font-weight: 600; color: var(--gold-500); letter-spacing: .08em; text-transform: uppercase; }
.nav-links { display: flex; gap: 4px; list-style: none; margin: 0; padding: 0; }
.nav-links a {
  display: block; padding: 8px 14px; border-radius: 8px;
  color: rgba(255, 255, 255, .82); font-size: 14.5px; font-weight: 500;
}
.nav-links a:hover { color: #fff; background: rgba(255, 255, 255, .08); text-decoration: none; }
.nav-links a.active { color: #fff; background: rgba(255, 255, 255, .12); }
.nav-toggle {
  display: none; background: none; border: 0; color: #fff; font-size: 24px;
  cursor: pointer; padding: 6px 10px; border-radius: 8px;
}

@media (max-width: 860px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none; position: absolute; top: var(--nav-h); left: 0; right: 0;
    flex-direction: column; gap: 0; padding: 8px 16px 16px;
    background: var(--navy-900); border-bottom: 1px solid rgba(255, 255, 255, .08);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 8px; }
}

/* ---------- Hero ---------- */
.hero {
  position: relative; overflow: hidden;
  min-height: 560px;
  display: flex; align-items: center;
  color: #fff;
  background: var(--navy-900) url("../assets/img/hero-1000-new.jpg") right center / cover no-repeat;
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(90deg, rgba(4, 20, 48, .92) 0%, rgba(4, 22, 54, .78) 38%, rgba(4, 24, 60, .25) 70%, rgba(4, 24, 60, 0) 100%);
}
.hero .container { position: relative; width: 100%; padding-top: 72px; padding-bottom: 72px; }
.hero-content { max-width: 640px; }
.eyebrow {
  display: inline-block; margin-bottom: 18px;
  font-size: 13px; font-weight: 600; letter-spacing: .12em; text-transform: uppercase;
  color: var(--gold-500);
}
.hero h1 { color: #fff; font-size: clamp(26px, 3vw, 36px); font-weight: 700; margin-bottom: 18px; }
.hero h1 .h1-acronym {
  background: linear-gradient(90deg, #ffffff 0%, #cfe2ff 55%, #f1d58e 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero .tagline { font-size: 18.5px; color: rgba(255, 255, 255, .88); max-width: 580px; margin-bottom: 30px; }
.hero-meta {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px 28px;
  max-width: 560px; margin: 0 0 34px; padding: 0;
}
.hero-meta div { border-left: 2px solid var(--gold-500); padding-left: 12px; }
.hero-meta dt { font-size: 12px; text-transform: uppercase; letter-spacing: .1em; color: rgba(255, 255, 255, .62); }
.hero-meta dd { margin: 2px 0 0; font-weight: 600; font-size: 15.5px; }
.hero-meta dd a { color: #fff; }
.btn-row { display: flex; flex-wrap: wrap; gap: 12px; }
.btn {
  display: inline-block; padding: 12px 22px; border-radius: 999px;
  font-weight: 600; font-size: 15px; border: 1px solid transparent;
  transition: background .15s, color .15s, border-color .15s;
}
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--gold-500); color: var(--navy-900); }
.btn-primary:hover { background: #ddb04a; }
.btn-ghost { border-color: rgba(255, 255, 255, .55); color: #fff; }
.btn-ghost:hover { background: rgba(255, 255, 255, .1); }
.btn-outline { border-color: var(--blue-600); color: var(--blue-600); }
.btn-outline:hover { background: var(--blue-50); }

@media (max-width: 760px) {
  .hero { min-height: 0; background-position: 70% center; }
  .hero::before { background: linear-gradient(180deg, rgba(4, 20, 48, .80) 0%, rgba(4, 20, 48, .90) 100%); }
  .hero .container { padding-top: 56px; padding-bottom: 56px; }
  .hero-meta { grid-template-columns: 1fr; }
}

/* ---------- Page header (sub-pages) ---------- */
.page-header {
  position: relative; color: #fff; padding: 64px 0 52px;
  background: var(--navy-900) url("../assets/img/hero-1000-new.jpg") right center / cover no-repeat;
}
.page-header::before {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(90deg, rgba(4, 20, 48, .95) 0%, rgba(4, 22, 54, .85) 50%, rgba(4, 24, 60, .55) 100%);
}
.page-header .container { position: relative; }
.page-header h1 { color: #fff; font-size: clamp(30px, 4vw, 42px); margin-bottom: 10px; }
.page-header p { color: rgba(255, 255, 255, .85); max-width: 720px; margin: 0; font-size: 17px; }
.breadcrumb { font-size: 13.5px; color: rgba(255, 255, 255, .65); margin-bottom: 14px; }
.breadcrumb a { color: rgba(255, 255, 255, .85); }

/* ---------- Sections ---------- */
.block { padding: 76px 0; }
.block.alt { background: var(--bg-alt); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.block.tight { padding: 56px 0; }
.section-title { font-size: clamp(26px, 3vw, 34px); margin-bottom: 12px; }
.section-title::after {
  content: ""; display: block; width: 48px; height: 3px; margin-top: 14px;
  background: var(--gold-500); border-radius: 2px;
}
.section-lead { color: var(--ink-soft); font-size: 17.5px; max-width: 800px; margin-bottom: 36px; }
.prose { max-width: 820px; color: var(--ink-soft); }
.prose p { margin-bottom: 1.1em; }
.prose strong { color: var(--ink); }
.highlight {
  margin: 28px 0 0; padding: 20px 24px; max-width: 820px;
  background: var(--blue-50); border-left: 4px solid var(--blue-600); border-radius: 0 var(--radius) var(--radius) 0;
  font-family: var(--serif); font-size: 19px; color: var(--navy-800);
}

/* ---------- Cards / grids ---------- */
.grid { display: grid; gap: 22px; }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
@media (max-width: 900px) { .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 620px) { .grid-3, .grid-2 { grid-template-columns: 1fr; } }

.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px 26px 24px; box-shadow: var(--shadow-sm);
}
.card h3 { font-size: 19.5px; margin-bottom: 8px; }
.card p { color: var(--ink-soft); margin: 0; font-size: 15.5px; }
.card .num {
  display: inline-flex; align-items: center; justify-content: center;
  width: 34px; height: 34px; margin-bottom: 14px; border-radius: 50%;
  background: var(--navy-800); color: var(--gold-500); font-weight: 700; font-family: var(--serif);
}

/* ---------- Key dates ---------- */
.dates { list-style: none; margin: 0; padding: 0; max-width: 820px; border-top: 2px solid var(--navy-800); }
.dates li {
  display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 20px; align-items: baseline;
  padding: 16px 4px; border-bottom: 1px solid var(--line);
}
.dates .date { font-weight: 700; color: var(--navy-800); font-family: var(--serif); font-size: 18px; }
.dates .what { color: var(--ink-soft); }
.dates .what strong { color: var(--ink); }
.dates li.featured { background: var(--gold-100); padding-left: 14px; padding-right: 14px; }
.note { font-size: 14.5px; color: var(--ink-mute); margin-top: 16px; }
@media (max-width: 620px) { .dates li { grid-template-columns: 1fr; gap: 2px; } }

/* ---------- People ---------- */
.people { display: grid; gap: 22px; grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 980px) { .people { grid-template-columns: repeat(3, minmax(0, 1fr)); } }
@media (max-width: 720px) { .people { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 420px) { .people { grid-template-columns: 1fr; } }
.person {
  display: flex; flex-direction: column; align-items: center; text-align: center;
  padding: 26px 18px 22px; background: #fff; border: 1px solid var(--line);
  border-radius: var(--radius); box-shadow: var(--shadow-sm);
  color: inherit; transition: transform .15s, box-shadow .15s;
}
a.person:hover { text-decoration: none; transform: translateY(-2px); box-shadow: var(--shadow-md); }
.person img, .person .placeholder {
  width: 132px; height: 132px; border-radius: 50%; object-fit: cover; object-position: center top;
  border: 3px solid #fff; box-shadow: 0 0 0 2px var(--blue-100), var(--shadow-sm); margin-bottom: 16px;
}
.person .placeholder {
  display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--navy-700), var(--blue-500)); color: #fff;
  font-family: var(--serif); font-size: 36px;
}
.person .pname { font-family: var(--serif); font-weight: 700; font-size: 18.5px; color: var(--navy-800); line-height: 1.3; }
.person .prole { font-size: 14px; color: var(--ink-soft); margin-top: 4px; line-height: 1.45; }
.person .ptag {
  margin-top: 10px; font-size: 12px; font-weight: 600; letter-spacing: .04em;
  color: var(--blue-600); background: var(--blue-50); padding: 3px 10px; border-radius: 999px;
}
.person.tba { border-style: dashed; background: transparent; box-shadow: none; justify-content: center; }
.person.tba .placeholder { background: var(--blue-100); color: var(--blue-600); }

/* Detailed bio rows (speakers / organizers pages) */
.bio-list { display: flex; flex-direction: column; gap: 22px; }
.bio {
  display: grid; grid-template-columns: 168px minmax(0, 1fr); gap: 30px; align-items: start;
  padding: 28px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow-sm);
}
.bio img, .bio .placeholder {
  width: 168px; height: 168px; border-radius: 50%; object-fit: cover; object-position: center top;
  border: 3px solid #fff; box-shadow: 0 0 0 2px var(--blue-100), var(--shadow-sm);
}
.bio h3 { font-size: 23px; margin-bottom: 2px; }
.bio h3 a { color: inherit; }
.bio .affil { color: var(--blue-600); font-weight: 600; font-size: 15.5px; margin-bottom: 14px; }
.bio p { color: var(--ink-soft); font-size: 15.5px; margin-bottom: .8em; }
.bio .talk {
  margin-top: 6px; padding: 10px 14px; border-radius: 8px; background: var(--gold-100);
  font-size: 15px; color: var(--ink);
}
.bio .talk b { color: var(--navy-800); }
.bio .links { display: flex; flex-wrap: wrap; gap: 8px 18px; font-size: 14.5px; font-weight: 600; margin-top: 8px; }
@media (max-width: 680px) {
  .bio { grid-template-columns: 1fr; justify-items: center; text-align: center; padding: 24px 20px; }
  .bio img, .bio .placeholder { width: 140px; height: 140px; }
  .bio .links { justify-content: center; }
  .bio p { text-align: left; }
}

.subhead { font-size: 24px; margin: 52px 0 22px; }
.subhead:first-child { margin-top: 0; }

/* ---------- Lists, misc ---------- */
.check-list { list-style: none; padding: 0; margin: 0; max-width: 820px; }
.check-list li { position: relative; padding: 0 0 12px 30px; color: var(--ink-soft); }
.check-list li::before {
  content: ""; position: absolute; left: 4px; top: .55em; width: 9px; height: 9px;
  border-radius: 2px; background: var(--blue-600); transform: rotate(45deg);
}
.check-list li strong { color: var(--ink); }

.info-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 22px; }
@media (max-width: 720px) { .info-grid { grid-template-columns: 1fr; } }
.info-grid .card ul { margin: 0; padding-left: 20px; color: var(--ink-soft); font-size: 15.5px; }
.info-grid .card li { margin-bottom: 6px; }

.cta {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 20px;
  padding: 30px 34px; border-radius: var(--radius);
  background: linear-gradient(120deg, var(--navy-800), var(--blue-600)); color: #fff;
}
.cta h3 { color: #fff; margin: 0 0 4px; font-size: 22px; }
.cta p { margin: 0; color: rgba(255, 255, 255, .85); }

.badge {
  display: inline-block; font-size: 12px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase;
  padding: 3px 10px; border-radius: 999px; background: var(--gold-100); color: #8a6512; vertical-align: middle;
}

.more-link { margin-top: 28px; font-weight: 600; }

/* ---------- Footer ---------- */
.site-footer { background: var(--navy-900); color: rgba(255, 255, 255, .72); padding: 44px 0; font-size: 14.5px; }
.site-footer .container { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 20px; }
.site-footer a { color: #fff; }
.site-footer .ft-title { color: #fff; font-family: var(--serif); font-size: 17px; font-weight: 700; margin-bottom: 4px; }

/* Two side-by-side text columns (Why WSDM) */
.prose.two-col { max-width: none; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 48px; }
@media (max-width: 760px) { .prose.two-col { grid-template-columns: 1fr; } }