/* =========================================================
   CONFLUENCE — Conference Design System
   Concept: the blackboard (lecture, live thought) resolves
   into the paper (the fixed proceedings). Hero lives on a
   dark chalkboard; the rest of the site lives on paper.
   ========================================================= */

:root{
  /* --- Color: named, used deliberately --- */
  --blackboard: #16241D;   /* hero / footer ground */
  --blackboard-line: #3C5445; /* chalk line on blackboard */
  --paper: #FAF8F2;        /* main background */
  --chalk: #F3F1E7;        /* text on blackboard */
  --ink: #2B3A67;          /* primary accent — links, headings on paper */
  --gold: #B4872A;         /* rare highlight — deadlines, active states */
  --graphite: #2B2B26;     /* body text on paper */
  --graphite-soft: #6B6B62;/* secondary text */
  --line: #DDD6C4;         /* hairline rule on paper */
  --card: #FFFFFF;

  /* --- Type --- */
  --font-display: "Fraunces", "Iowan Old Style", serif;
  --font-body: "Source Serif 4", Georgia, serif;
  --font-mono: "IBM Plex Mono", ui-monospace, monospace;

  /* --- Scale --- */
  --step-0: clamp(1rem, 0.95rem + 0.2vw, 1.05rem);
  --step-1: clamp(1.2rem, 1.1rem + 0.4vw, 1.4rem);
  --step-2: clamp(1.6rem, 1.4rem + 0.8vw, 2rem);
  --step-3: clamp(2.2rem, 1.8rem + 1.6vw, 3.2rem);
  --step-4: clamp(2.8rem, 2.1rem + 3vw, 4.6rem);

  --maxw: 1100px;
  --radius: 3px;
}

*{ box-sizing: border-box; }
html{ scroll-behavior: smooth; }
body{
  margin:0;
  background: var(--paper);
  color: var(--graphite);
  font-family: var(--font-body);
  font-size: var(--step-0);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img{ max-width:100%; display:block; }
a{ color: var(--ink); }
.wrap{ max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

h1,h2,h3,h4{
  font-family: var(--font-display);
  color: var(--graphite);
  line-height: 1.1;
  margin: 0 0 .5em;
  font-weight: 600;
}
h1{ font-size: var(--step-4); }
h2{ font-size: var(--step-3); }
h3{ font-size: var(--step-2); }
p{ margin: 0 0 1em; }

/* Focus visibility (never remove) */
a:focus-visible, button:focus-visible, input:focus-visible,
textarea:focus-visible, select:focus-visible{
  outline: 2px solid var(--gold);
  outline-offset: 3px;
}

@media (prefers-reduced-motion: reduce){
  *{ animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; scroll-behavior:auto !important; }
}

/* --- Section label: "§ n — Title", authentic to a math paper's
   sectioning, doubles as the site's structural device --- */
.section-label{
  font-family: var(--font-mono);
  font-size: .8rem;
  letter-spacing: .04em;
  color: var(--ink);
  text-transform: uppercase;
  display:flex; align-items:center; gap:.6em;
  margin-bottom: .9em;
}
.section-label::before{ content: "§"; color: var(--gold); font-size: 1.1em; }

section{ padding: 88px 0; border-bottom: 1px solid var(--line); }
section:last-of-type{ border-bottom:none; }

/* =============== NAV =============== */
header.site-nav{
  position: sticky; top:0; z-index: 50;
  background: rgba(250,248,242,.92);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--line);
}
.nav-inner{
  max-width: var(--maxw); margin:0 auto; padding: 16px 24px;
  display:flex; align-items:center; justify-content:space-between;
}
.brand{
  font-family: var(--font-display);
  font-weight: 700; font-size: 1.2rem; color: var(--graphite);
  text-decoration:none; letter-spacing: -.01em;
}
.brand em{ font-style: normal; color: var(--ink); }
.nav-links{ display:flex; gap: 28px; list-style:none; margin:0; padding:0; }
.nav-links a{
  text-decoration:none; color: var(--graphite);
  font-family: var(--font-mono); font-size: .82rem; letter-spacing:.03em;
  text-transform: uppercase; padding: 6px 2px; border-bottom: 2px solid transparent;
}
.nav-links a:hover, .nav-links a[aria-current="page"]{ border-bottom-color: var(--gold); }
.nav-toggle{ display:none; }

@media (max-width: 760px){
  .nav-links{
    position:absolute; top:100%; left:0; right:0;
    flex-direction:column; background: var(--paper);
    border-bottom: 1px solid var(--line);
    padding: 8px 24px 20px; gap: 14px;
    display:none;
  }
  .nav-links.open{ display:flex; }
  .nav-toggle{
    display:inline-flex; background:none; border:1px solid var(--line);
    border-radius: var(--radius); padding: 8px 10px; cursor:pointer;
    font-family: var(--font-mono); font-size: .9rem;
  }
}

/* =============== HERO (blackboard) =============== */
.hero{
  background:
    radial-gradient(ellipse at 15% 20%, rgba(255,255,255,0.04), transparent 45%),
    var(--blackboard);
  color: var(--chalk);
  padding: 96px 0 72px;
  position: relative;
  overflow: hidden;
  border-bottom: 6px solid var(--gold);
}
.hero .wrap{ position:relative; z-index:2; }
.hero-eyebrow{
  font-family: var(--font-mono); font-size: .85rem; letter-spacing:.08em;
  text-transform: uppercase; color: #C9D6C7; margin-bottom: 18px;
  display:flex; gap: 14px; flex-wrap:wrap;
}
.hero-eyebrow span{ opacity:.85; }
.hero h1{
  color: var(--chalk); font-size: var(--step-4); max-width: 15ch;
  margin-bottom: .3em;
}
.hero h1 .accent{ color: #E8C874; font-style: italic; }
.hero p.lede{
  font-family: var(--font-body); font-size: 1.15rem; max-width: 56ch;
  color: #DCE3D8; margin-bottom: 2em;
}
.hero-actions{ display:flex; gap: 16px; flex-wrap:wrap; margin-bottom: 3em; }

.btn{
  display:inline-block; font-family: var(--font-mono); font-size: .85rem;
  letter-spacing:.03em; text-transform: uppercase; text-decoration:none;
  padding: 13px 22px; border-radius: var(--radius); border: 1px solid transparent;
  cursor:pointer; transition: transform .15s ease, background .15s ease;
}
.btn:hover{ transform: translateY(-1px); }
.btn-primary{ background: var(--gold); color: #1B1503; font-weight:600; }
.btn-primary:hover{ background:#C7972E; }
.btn-ghost{ border-color: rgba(243,241,231,.4); color: var(--chalk); }
.btn-ghost:hover{ border-color: var(--chalk); }
.btn-dark{ background: var(--blackboard); color: var(--chalk); }
.btn-dark:hover{ background:#0F1A14; }

/* Hand-drawn chalk sketch behind hero title */
.chalk-sketch{ position:absolute; inset:0; z-index:1; opacity:.55; pointer-events:none; }
.chalk-sketch path, .chalk-sketch circle{ stroke: #7C9587; }

/* Equidistribution motif: points {n*alpha mod 1} placed around a circle via
   an irrational rotation — the classical picture of Weyl equidistribution.
   Kept faint and out of the way; it's texture, not a diagram to read. */
.equidist-bg{ opacity: .16; }
.equidist-bg circle{ fill: #E8C874; stroke: none; }

/* Key-dates strip inside hero */
.key-dates{
  display:grid; grid-template-columns: repeat(auto-fit, minmax(150px,1fr));
  gap: 1px; background: rgba(243,241,231,.15);
  border: 1px solid rgba(243,241,231,.2); border-radius: var(--radius);
  overflow:hidden;
}
.key-dates > div{ background: rgba(22,36,29,.6); padding: 16px 18px; }
.key-dates .label{ font-family: var(--font-mono); font-size:.72rem; text-transform:uppercase; color:#9FB29B; letter-spacing:.05em; }
.key-dates .value{ font-family: var(--font-mono); font-size: 1.05rem; color: var(--chalk); margin-top:4px; }

/* =============== CARDS / GRID =============== */
.grid{ display:grid; gap: 28px; }
.grid-3{ grid-template-columns: repeat(3, 1fr); }
.grid-2{ grid-template-columns: repeat(2, 1fr); }
@media (max-width: 860px){ .grid-3, .grid-2{ grid-template-columns: 1fr; } }

.card{
  background: var(--card); border: 1px solid var(--line);
  border-radius: var(--radius); padding: 26px;
}

.speaker-card{ text-align:left; }
.speaker-photo{
  width:100%; aspect-ratio: 4/3; object-fit:cover;
  border-radius: var(--radius); margin-bottom: 14px;
  background: var(--blackboard-line);
}
.speaker-card h4{ margin-bottom:.15em; font-size: 1.15rem; }
.speaker-affil{ font-family: var(--font-mono); font-size:.78rem; color: var(--graphite-soft); text-transform:uppercase; letter-spacing:.03em; margin-bottom:.6em; }
.speaker-talk{ font-style: italic; color: var(--ink); margin-bottom:0; }

/* =============== SCHEDULE =============== */
.day-tabs{ display:flex; gap:10px; flex-wrap:wrap; margin-bottom: 28px; }
.day-tab{
  font-family: var(--font-mono); font-size:.8rem; text-transform:uppercase;
  padding: 9px 16px; border:1px solid var(--line); border-radius: 999px;
  background:none; cursor:pointer; color: var(--graphite-soft);
}
.day-tab[aria-selected="true"]{ background: var(--ink); color:#fff; border-color: var(--ink); }

.session{
  display:grid; grid-template-columns: 110px 1fr; gap: 20px;
  padding: 18px 0; border-top: 1px solid var(--line);
}
.session:first-of-type{ border-top:none; }
.session-time{ font-family: var(--font-mono); font-size:.85rem; color: var(--gold); font-weight:600; }
.session-title{ margin:0 0 .2em; font-family: var(--font-display); font-size:1.15rem; font-weight:600; }
.session-meta{ font-family: var(--font-mono); font-size:.75rem; color: var(--graphite-soft); text-transform:uppercase; letter-spacing:.03em; }
.session-track{
  display:inline-block; font-family: var(--font-mono); font-size:.68rem;
  padding: 2px 8px; border-radius: 999px; margin-right:8px;
  background: rgba(43,58,103,.08); color: var(--ink);
}

/* Schedule grid — homepage "Schedule at a glance" table: all days at once */
.schedule-table-wrap{ overflow-x: auto; }
.schedule-table{ width:100%; border-collapse: collapse; font-size:.88rem; }
.schedule-table th, .schedule-table td{
  padding: 10px 14px; border-bottom: 1px solid var(--line);
  text-align:left; vertical-align:middle; white-space:nowrap;
}
.schedule-table thead th{
  font-family: var(--font-mono); font-size:.68rem; text-transform:uppercase;
  letter-spacing:.03em; color: var(--graphite-soft); border-bottom: 2px solid var(--line);
}
.schedule-table td.time{
  font-family: var(--font-mono); font-size:.75rem; color: var(--gold); font-weight:600;
}
.schedule-table tbody tr:last-child td{ border-bottom: none; }
.schedule-table tr.break-row td{
  font-family: var(--font-mono); font-size:.7rem; text-transform:uppercase;
  letter-spacing:.03em; font-style: normal; color: var(--graphite-soft);
  background: rgba(43,58,103,.03); text-align:center;
}

/* Talks (titles + abstracts) */
[id]{ scroll-margin-top: 100px; }
.talk-entry{ padding: 34px 0; border-top: 1px solid var(--line); }
.talk-entry:first-of-type{ border-top: none; padding-top: 0; }
.talk-title{ font-size: 1.35rem; margin-bottom: .3em; }
.talk-note{
  font-family: var(--font-mono); font-size:.72rem; text-transform:uppercase;
  letter-spacing:.03em; color: var(--gold); margin: .6em 0 1em;
}
.talk-abstract p{ max-width: 70ch; color: var(--graphite); }
.talk-abstract mjx-container{ font-size: 100% !important; }
.talk-slides-link{ margin-top: 1em; }
.talk-slides-link a{
  font-family: var(--font-mono); font-size:.82rem; text-transform:uppercase;
  letter-spacing:.03em; text-decoration:none; color: var(--ink);
  border-bottom: 1px solid var(--line); padding-bottom: 2px;
}
.talk-slides-link a:hover{ border-bottom-color: var(--ink); }

.talk-zoom{
  margin-top: 1.2em; padding: 16px 18px; border: 1px solid var(--line);
  border-left: 3px solid var(--gold); border-radius: var(--radius);
  background: rgba(180,135,42,.04); max-width: 60ch;
}
.talk-zoom-heading{
  font-family: var(--font-mono); font-size:.72rem; text-transform:uppercase;
  letter-spacing:.05em; color: var(--gold); margin: 0 0 .6em;
}
.talk-zoom-line{ font-size:.92rem; margin: 0 0 .4em; color: var(--graphite); }
.talk-zoom-line:last-child{ margin-bottom: 0; }
.talk-zoom-line a{ color: var(--ink); }
.session-title a{ color: var(--graphite); text-decoration: underline; text-decoration-color: var(--line); text-underline-offset: 3px; }
.session-title a:hover{ color: var(--ink); text-decoration-color: var(--ink); }

/* =============== NEWS / LIST =============== */
.news-item{ padding: 18px 0; border-top: 1px solid var(--line); display:grid; grid-template-columns: 130px 1fr; gap:18px; }
.news-item:first-of-type{ border-top:none; }
.news-date{ font-family: var(--font-mono); font-size:.78rem; color: var(--graphite-soft); }

/* =============== FOOTER =============== */
footer.site-footer{
  background: var(--blackboard); color: var(--chalk);
  padding: 56px 0 30px;
}
footer.site-footer a{ color: var(--chalk); }
.footer-grid{ display:grid; grid-template-columns: 2fr 1fr 1fr; gap: 32px; margin-bottom: 40px; }
@media (max-width: 700px){ .footer-grid{ grid-template-columns:1fr; } }
.footer-logos{
  display:flex; align-items:center; gap: 22px; flex-wrap:wrap;
  background: var(--chalk); border-radius: var(--radius);
  padding: 14px 20px; margin: 14px 0; width:fit-content;
}
.footer-logos img{ height: 48px; width:auto; }
.footer-logos img:first-child{ height: 58px; }
footer.site-footer h4{ color:#C9D6C7; font-family: var(--font-mono); font-size:.78rem; text-transform:uppercase; letter-spacing:.05em; margin-bottom:1em; }
footer.site-footer ul{ list-style:none; margin:0; padding:0; }
footer.site-footer li{ margin-bottom:.6em; }
.footer-bottom{
  border-top: 1px solid var(--blackboard-line); padding-top: 20px;
  font-family: var(--font-mono); font-size:.75rem; color:#8FA189;
  display:flex; justify-content:space-between; flex-wrap:wrap; gap:10px;
}

/* =============== FORM (registration/contact) =============== */
form.stack{ display:flex; flex-direction:column; gap:18px; max-width: 560px; }
.field label{ display:block; font-family: var(--font-mono); font-size:.78rem; text-transform:uppercase; letter-spacing:.03em; margin-bottom:6px; color: var(--graphite-soft); }
.field input, .field select, .field textarea{
  width:100%; padding: 11px 12px; border:1px solid var(--line); border-radius: var(--radius);
  font-family: var(--font-body); font-size: 1rem; background:#fff; color: var(--graphite);
}
.field textarea{ min-height:120px; resize:vertical; }

/* Loading / empty states */
.state-msg{ font-family: var(--font-mono); font-size:.85rem; color: var(--graphite-soft); padding: 20px 0; }

.pill{ display:inline-block; font-family: var(--font-mono); font-size:.7rem; text-transform:uppercase; padding:3px 10px; border-radius:999px; border:1px solid var(--line); color: var(--graphite-soft); }