/* Minimal, readable, and GitHub-Pages-friendly. */
:root{
  --bg: #ffffff;
  --bg2:#f8fafc;     /* slate-50 */
  --card:#ffffff;
  --card2:#f1f5f9;   /* slate-100 */
  --text:#0f172a;    /* slate-900 */
  --muted:#475569;   /* slate-600 */
  --line: rgba(15,23,42,.12);
  --accent:#0284c7;  /* sky-600 */
  --accent2:#7c3aed; /* violet-600 */
  --shadow: 0 12px 34px rgba(2,6,23,.10);
  --radius: 18px;
  --max: 1080px;
  --font: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: var(--font);
  background: radial-gradient(1200px 700px at 20% -10%, rgba(2,132,199,.10), transparent 60%),
              radial-gradient(1000px 600px at 90% 10%, rgba(124,58,237,.10), transparent 55%),
              linear-gradient(180deg, var(--bg), var(--bg2) 60%);
  color: var(--text);
  line-height: 1.6;
}

a{color:inherit; text-decoration:none}
a:hover{opacity:.92}

.container{max-width: var(--max); margin:0 auto; padding: 0 18px;}
.section{padding: 64px 0}
.section--alt{background: linear-gradient(180deg, var(--bg2), rgba(248,250,252,0));}

h1,h2,h3{line-height:1.15; margin:0 0 14px}
h2{font-size: clamp(1.4rem, 2.5vw, 2.1rem)}
h3{font-size: 1.1rem}
p{margin: 0 0 12px}
.muted{color: var(--muted)}
.dot{opacity:.6}

/* Top bar */
.topbar{
  position: sticky; top:0; z-index:10;
  backdrop-filter: blur(10px);
  background: rgba(255,255,255,.78);
  border-bottom: 1px solid var(--line);
  padding: 12px 0;
}
.topbar .container{display:flex; align-items:center; justify-content:space-between}
.brand{
  display:flex; align-items:baseline; gap: 10px;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid rgba(15,23,42,.12);
  background: rgba(255,255,255,.72);
}
.brand__mark{font-weight:700; letter-spacing:.2px}
.brand__sep{opacity:.6}
.brand__sub{opacity:.9}

.nav{
  display:flex; gap: 14px; align-items:center;
  padding: 8px 14px;
}
.nav a{
  opacity:.88;
  padding: 8px 10px;
  border-radius: 10px;
  border: 1px solid transparent;
}
.nav a:hover{
  opacity:1;
  border-color: rgba(15,23,42,.12);
  background: rgba(2,6,23,.04);
}
.nav__cta{
  border-color: rgba(2,132,199,.30) !important;
  background: rgba(2,132,199,.10);
}

/* Hero */
.hero{
  position: relative;
  min-height: 82vh;
  display:flex;
  align-items: center;
  overflow:hidden;
  border-bottom: 1px solid var(--line);
}
.hero__bg{
  position:absolute; inset:0;
  background-image: url("assets/cover.jpg");
  background-size: cover;
  background-position: center;
  filter: saturate(1.05) contrast(1.05);
  transform: scale(1.03);
}
.hero__overlay{
  position:absolute; inset:0;
  background: linear-gradient(90deg, rgba(255,255,255,.92), rgba(255,255,255,.62) 55%, rgba(255,255,255,.20));
}
.hero__content{
  position:relative;
  max-width: var(--max);
  margin:0 auto;
  padding: 92px 18px 62px;
}
.badge{
  display:inline-flex;
  gap:10px;
  font-size:.92rem;
  color: var(--muted);
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid rgba(15,23,42,.12);
  background: rgba(255,255,255,.78);
}
.hero h1{
  margin-top: 14px;
  font-size: clamp(2.0rem, 4vw, 3.2rem);
  letter-spacing: .2px;
}
.lead{
  max-width: 68ch;
  font-size: 1.05rem;
  color: rgba(15,23,42,.86);
}

.hero__actions{
  display:flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
}
.button{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  padding: 10px 14px;
  border-radius: 14px;
  border: 1px solid rgba(15,23,42,.14);
  background: rgba(255,255,255,.78);
  box-shadow: 0 10px 24px rgba(2,6,23,.10);
  font-weight: 600;
}
.button.primary{
  border-color: rgba(2,132,199,.35);
  background: linear-gradient(90deg, rgba(2,132,199,.14), rgba(124,58,237,.12));
}
.button.ghost{
  background: rgba(2,6,23,.04);
}
.button:hover{transform: translateY(-1px)}
.button:active{transform: translateY(0px)}

.hero__stats{
  margin-top: 22px;
  display:grid;
  grid-template-columns: repeat(3, minmax(0,1fr));
  gap: 12px;
  max-width: 860px;
}
.stat{
  border: 1px solid rgba(15,23,42,.12);
  background: rgba(255,255,255,.78);
  border-radius: var(--radius);
  padding: 14px 14px;
}
.stat__k{font-size:.85rem; color: var(--muted)}
.stat__v{font-weight:700}

/* Cards & grids */
.card{
  border: 1px solid rgba(15,23,42,.10);
  background: linear-gradient(180deg, rgba(255,255,255,1), rgba(248,250,252,1));
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}
.grid2{
  display:grid;
  grid-template-columns: repeat(2, minmax(0,1fr));
  gap: 14px;
  margin-top: 12px;
}
.grid3{
  display:grid;
  grid-template-columns: repeat(3, minmax(0,1fr));
  gap: 14px;
  margin-top: 12px;
}
.nice{margin:0; padding-left: 18px}
.nice li{margin: 6px 0}

.formula{
  margin: 10px 0 14px;
  padding: 12px 14px;
  border-radius: 14px;
  border: 1px solid rgba(2,132,199,.20);
  background: rgba(2,132,199,.08);
  overflow:auto;
}
.formula code{
  font-size: 1rem;
  color: var(--text);
}

/* Timeline */
.timeline{display:flex; flex-direction:column; gap: 10px}
.trow{
  display:grid;
  grid-template-columns: 120px 1fr;
  gap: 12px;
  padding: 10px 12px;
  border-radius: 14px;
  border: 1px solid rgba(15,23,42,.10);
  background: rgba(255,255,255,.78);
}
.tdate{
  font-weight: 800;
  color: rgba(2,132,199,.95);
  letter-spacing: .2px;
}
.titem{color: rgba(15,23,42,.88)}

/* Organizers */
.org-grid{
  display:grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}
.org{
  padding: 14px;
  border-radius: 16px;
  border: 1px solid rgba(15,23,42,.10);
  background: rgba(255,255,255,.78);
}
.org__name{font-weight: 800}
.org__affil{color: var(--muted); font-size:.92rem}
.org__email{
  display:inline-block;
  margin-top: 6px;
  color: rgba(2,132,199,.95);
  font-size: .94rem;
  word-break: break-word;
}

/* QR */
.qr{
  display:flex;
  flex-direction:column;
  align-items:center;
  gap: 10px;
}
.qr img{
  width: min(320px, 100%);
  border-radius: 18px;
  border: 1px solid rgba(255,255,255,.16);
  background: white;
}
.qr__caption{color: var(--muted); font-size:.92rem}

/* Footer */
.footer{
  padding: 32px 0;
  border-top: 1px solid var(--line);
  background: var(--bg2);
}
.footer__inner{
  display:flex;
  justify-content:space-between;
  align-items:flex-start;
  gap: 14px;
}
.footer__title{font-weight:800}
.footer__meta{color: var(--muted); font-size:.92rem}
.footer__right a{color: rgba(2,132,199,.95)}

/* Responsive */
@media (max-width: 920px){
  .nav{display:none}
  .hero__stats{grid-template-columns: 1fr}
  .grid3{grid-template-columns: 1fr}
  .grid2{grid-template-columns: 1fr}
  .org-grid{grid-template-columns: 1fr}
  .hero__overlay{
    background: linear-gradient(180deg, rgba(255,255,255,.94), rgba(255,255,255,.78) 55%, rgba(255,255,255,.58));
  }
}