:root{
  --bg: #ffffff;
  --text: #111;
  --muted: #555;
  --accent: #2b6cb0;
  --max: 900px;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial;
}

*{box-sizing:border-box}
body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  line-height:1.45;
}

/* container */
.container{
  max-width:var(--max);
  margin:0 auto;
  padding:28px 20px;
}

/* header / nav */
.site-header{
  position:sticky;
  top:0;
  background:white;
  border-bottom:1px solid #eee;
  z-index:30;
}
.header-inner{
  display:flex;
  align-items:center;
  gap:12px;
  justify-content:space-between;
}
.brand{
  font-weight:700;
  font-size:18px;
  padding:12px 0;
}
.nav{
  display:flex;
  gap:12px;
  align-items:center;
}
.nav a{
  text-decoration:none;
  color:var(--muted);
  padding:8px 10px;
  border-radius:6px;
  font-weight:600;
}
.nav a:hover{ color:var(--text); background:#f4f8ff; }
.cta{
  background:var(--accent);
  color:white !important;
  padding:8px 12px;
  border-radius:8px;
}

/* hero */
.hero{
  padding-top:28px;
  padding-bottom:12px;
}
.hero h1{
  font-size:48px;
  margin:4px 0 8px 0;
  line-height:1;
}
.lead{ color:var(--muted); margin:0 0 6px 0; }

/* cards */
.card{
  background:#fff;
  border-radius:8px;
  padding:18px;
  margin:16px 0;
  box-shadow: 0 6px 18px rgba(10,10,10,0.03);
}
.speakers-grid{ display:flex; gap:12px; flex-wrap:wrap; }
.speaker{ flex:1 1 220px; padding:8px; border-left:3px solid #f1f5f9; }
.speaker-name{ font-weight:700 }

/* big button */
.big-button{
  display:inline-block;
  padding:12px 18px;
  text-decoration:none;
  font-weight:700;
  border-radius:8px;
  border:1px solid rgba(0,0,0,0.06);
  background:var(--accent);
  color:#fff;
}

/* footer */
.site-footer{ text-align:center; color:var(--muted); padding:26px 0; font-size:14px; }

/* mobile nav toggle (CSS-only hamburger) */
#nav-toggle{ display:none; }
.nav-toggle-label{
  display:none;
  width:36px;
  cursor:pointer;
  padding:10px;
}
.nav-toggle-label span{
  display:block;
  height:3px;
  margin:6px 0;
  background:#333;
  border-radius:3px;
}

/* responsive */
@media (max-width:720px){
  .nav{ display:none; position:absolute; right:12px; top:64px; background:white; flex-direction:column; padding:12px; border-radius:8px; box-shadow:0 8px 24px rgba(0,0,0,0.08); }
  #nav-toggle:checked + .nav-toggle-label + .nav { display:flex; }
  .nav-toggle-label{ display:block; }
  .header-inner{ gap:8px; }
  .hero h1{ font-size:36px; }
}

/* schedule grid and small helpers */
.schedule-grid{ display:grid; grid-template-columns: 1fr 220px 1fr; gap:12px; align-items:start; }
.schedule-time{ font-weight:700; text-align:right; padding-right:10px; }
.schedule-item{ padding-left:12px; }
.note{ color:#555; font-size:0.95rem; margin-top:6px; }
.sponsor-row{ display:flex; gap:12px; align-items:center; flex-wrap:wrap; margin-top:12px; }
.sponsor{ padding:8px 12px; border-radius:6px; background:#f8fafc; border:1px solid #eef2f6; font-weight:600;}
/* small responsive tweak */
@media (max-width:900px){ .schedule-grid{ grid-template-columns: 1fr; } .schedule-time{ text-align:left; padding-right:0; } }