@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');
:root {
  --bg: #f0f7ff;
  --card: #f7fbff;
  --accent: #60a5fa;
  --accent-2: #93c5fd;
  --text: #1f2937;
  --muted: #4b5563;
  --border: #cfe3ff;
  --shadow: 0 10px 30px rgba(0,0,0,0.08);
}

@media (max-width: 640px) {
  /* Ensure mobile nav is horizontally scrollable and does not exceed viewport */
  .nav-list {
    display: flex !important;
    position: static;
    gap: 8px;
    padding: 0 10px;
    overflow-x: auto;
    white-space: nowrap;
    flex-wrap: nowrap;
    -webkit-overflow-scrolling: touch;
    touch-action: pan-x;
    background: transparent;
    border: 0;
    border-radius: 0;
    box-shadow: none;
  }
  .nav-list::-webkit-scrollbar { display: none; }
  .nav-list > li { flex: 0 0 auto; }
  .nav-list > li > a,
  .nav-list > li > .dropdown-toggle { padding: 0 12px; }
}

* { box-sizing: border-box; }
html, body { height: 100%; overflow-x: hidden; }
body {
  margin: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: linear-gradient(180deg, #f0f7ff 0%, #eaf3ff 100%);
  padding-top: 64px; /* compensate fixed header height */
}

.container {
  width: 100%;
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 12px;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; border-radius: 12px; }

/* Header */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(200, 225, 255, 0.78);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.logo { font-weight: 700; letter-spacing: 0.5px; }
.nav-list { display: flex; gap: 18px; list-style: none; padding: 0; margin: 0; flex-wrap: nowrap; }
.nav-toggle { display: none; }


.nav a { color: var(--muted); white-space: nowrap; font-size: 16px; }
.nav a:hover { color: var(--text); }

/* Dropdown */
.dropdown { position: relative; margin-left: 14px; }
.nav-list > li > a,
.nav-list > li > .dropdown-toggle {
  display: inline-flex;
  align-items: center;
  height: 40px;
  padding: 0 10px;
}
.dropdown-toggle {
  color: #0f172a; /* 深色文字 */
  background: #bcd7ff; /* 更深的浅蓝背景，区分导航背景 */
  border: 1px solid #9ec3ff;
  border-radius: 10px;
  padding: 0 10px;
  cursor: pointer;
}
.dropdown-toggle:hover {
  background: #9ec3ff;
  color: #0f172a;
}
.dropdown-menu {
  position: absolute;
  right: 0;
  top: calc(100% + 8px);
  min-width: 200px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  padding: 8px;
  margin: 0;
  list-style: none;
  display: none;
}
.dropdown.open .dropdown-menu { display: grid; gap: 8px; }
.dropdown-menu a { color: var(--muted); }
.dropdown-menu a:hover { color: var(--text); }
.btn {
  display: inline-block; padding: 10px 16px; border-radius: 10px;
  border: 1px solid var(--border); transition: transform 0.1s ease, background 0.2s ease, color 0.2s ease;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: var(--accent); color: white; border-color: transparent; }
.btn-primary:hover { background: #3b82f6; }
.btn-secondary { background: var(--card); color: var(--text); }

/* Hero */
.hero {
  min-height: 420px;
  padding: 96px 0;
  background-image: url('san_diego.jpg');
  background-size: cover;
  background-position: center;
  position: relative;
}
.hero-inner { display: block; }
.hero-text h1 { font-size: 42px; margin: 0 0 10px; }
.hero-text p { color: var(--muted); margin: 0 0 16px; }
.hero-actions { display: flex; gap: 12px; }

/* Hero overlay/content */
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0.35), rgba(0,0,0,0.25));
  z-index: 0;
}
.hero-overlay { position: relative; }
.hero-content { max-width: 840px; }
.hero-content h1 { color: #ffffff; font-size: 48px; margin: 0 0 12px; }
.hero-content .hero-title { color: #8cfff6; }
.hero-content p { color: #e5e7eb; margin: 0 0 16px; }

/* Hero typography */
.hero-title { font-size: 56px; line-height: 1.1; color: #ff3b30; }
.hero-line2 { font-size: 32px; line-height: 1.3; color: #e5e7eb; white-space: nowrap; }
.hero-line3, .hero-line4 { font-size: 18px; line-height: 1.5; color: #e5e7eb; }

.hero-credit {
  position: absolute;
  right: 12px;
  bottom: 12px;
  font-size: 12px;
  color: #ffffff;
  background: rgba(0,0,0,0.35);
  padding: 6px 8px;
  border-radius: 6px;
  z-index: 1;
}

.section {
  padding: 40px 0;
}
.section-alt {
  background: radial-gradient(1200px 400px at 20% -100%, rgba(96,165,250,0.18), transparent 60%),
              radial-gradient(900px 400px at 120% -120%, rgba(147,197,253,0.18), transparent 60%);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.section-title {
  font-size: 28px; margin: 0 0 14px;
}
.section-desc { color: var(--muted); margin: 0 0 24px; }
#about .section-desc { line-height: 1.8; }

.cfp-box {
  border: 1px solid rgba(15, 23, 42, 0.12);
  background: rgba(232, 242, 255, 0.55);
  border-radius: 12px;
  padding: 16px 20px;
  box-shadow: 0 6px 18px rgba(0, 0, 0, 0.06);
  margin: 16px 0;
}
.cfp-box h3 { margin-top: 0; }
.cfp-box ol, .cfp-box ul { padding-left: 20px; margin: 12px 0 0; }
.cfp-box p { margin: 10px 0; }
#cfp .cfp-box:nth-of-type(2) p { line-height: 1.8; }
.cfp-sep { border: 0; border-top: 1px solid var(--border); margin: 12px 0; }
.section-sep { border: 0; border-top: 1px solid var(--border); margin: 12px 0; }
.highlight-red { color: #ff3b30; }
.cfp-box > ul > li { margin: 14px 0; }
.cfp-box > ul > li:last-child { margin-bottom: 0; }
.cfp-box > ul > li > ul { margin-top: 8px; }

@media (max-width: 640px) {
  .cfp-box { padding: 14px 16px; border-radius: 10px; }
}

.feature-grid {
  display: grid; grid-template-columns: repeat(3,1fr); gap: 16px;
}
.feature-card {
  background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 16px;
  box-shadow: var(--shadow);
}
.feature-card h3 { margin: 0 0 6px; font-size: 18px; }
.feature-card p { margin: 0; color: var(--muted); }

/* Timeline */
.timeline { display: grid; grid-template-columns: 1fr; gap: 12px; }
.timeline-item {
  display: grid; grid-template-columns: 180px 1fr; gap: 16px;
  background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 16px; box-shadow: var(--shadow);
}
.timeline-item .time { color: var(--accent-2); font-weight: 600; }
.timeline-item .content h3 { margin: 0 0 6px; }
.timeline-item .content p { margin: 0; color: var(--muted); }

/* Speakers */
.speaker-grid {
  display: grid; grid-template-columns: repeat(3,1fr); gap: 16px;
}

/* Keynotes: stacked items, each with left image and right text */
#keynotes .keynote-list { display: grid; gap: 24px; }
#keynotes .keynote-item {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 20px;
  align-items: center;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  box-shadow: var(--shadow);
}
#keynotes .keynote-media img {
  width: 100%;
  height: auto;
  border-radius: 12px;
  display: block;
}
#keynotes .keynote-info h3 { margin: 0 0 8px; font-size: 20px; }
#keynotes .keynote-info p { margin: 0; color: var(--muted); }
#organizers .committee-grid {
  grid-template-columns: repeat(4,1fr);
}
#organizers .speaker-grid:first-of-type {
  grid-template-columns: repeat(4,1fr);
}
.speaker-card {
  background: var(--card); border: 1px solid var(--border); border-radius: 14px; overflow: hidden; box-shadow: var(--shadow);
}
.speaker-info { padding: 12px; }
.speaker-info h3 { margin: 0 0 6px; font-size: 18px; }
.speaker-info p { margin: 0; color: var(--muted); }

/* Organizers: round avatars 250x250 */
#organizers .speaker-card img {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  object-fit: cover;
  display: block;
  margin: 12px auto;
}
#organizers .speaker-info { text-align: center; }
#organizers .speaker-grid { gap: 36px; }


#organizers .speaker-card {
  background: transparent;
  border: 0;
  box-shadow: none;
  border-radius: 0;
}





/* Form styles removed per request */

/* Footer */
.site-footer { border-top: 1px solid var(--border); }
.footer-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 72px;
}
.footer-links { display: flex; gap: 12px; list-style: none; padding: 0; margin: 0; }
.footer-links a { color: var(--muted); }
.footer-links a:hover { color: var(--text); }

/* Responsive */
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; }
  .feature-grid, .speaker-grid { grid-template-columns: 1fr 1fr; }
  /* Ensure organizers (including Student Chairs as first-of-type) wrap to two columns on tablets */
  #organizers .speaker-grid,
  #organizers .speaker-grid:first-of-type,
  #organizers .committee-grid { grid-template-columns: 1fr 1fr; }
  #organizers .speaker-grid,
  #organizers .committee-grid { grid-template-columns: 1fr 1fr; }
  #keynotes .keynote-item { grid-template-columns: 1fr; }
  .timeline-item { grid-template-columns: 1fr; }
  .container { padding: 0 12px; }
  .nav-list { gap: 10px; }
  .nav a { font-size: 13px; }
  .hero-content { max-width: 100%; }
  .hero-line2 {
    white-space: normal !important;
    overflow-wrap: anywhere;
    word-wrap: break-word;
    word-break: break-all;
    hyphens: auto;
    display: block;
    max-width: 100%;
  }
}

@media (max-width: 640px) {
  .nav-toggle { display: none; }
  .nav-list { 
    display: flex; 
    position: static; right: auto; top: auto; 
    background: transparent; border: 0; border-radius: 0; padding: 0; box-shadow: none; 
    gap: 8px; 
    overflow-x: auto; 
    white-space: nowrap; 
    -webkit-overflow-scrolling: touch; 
    scrollbar-width: none; 
  }
  .nav-list.show { display: grid; gap: 8px; }
  .speaker-grid { grid-template-columns: 1fr; }
  /* Force organizers (including Student Chairs as first-of-type) to single column on phones */
  #organizers .speaker-grid,
  #organizers .speaker-grid:first-of-type,
  #organizers .committee-grid { grid-template-columns: 1fr; }
  #organizers .speaker-grid,
  #organizers .committee-grid { grid-template-columns: 1fr; }
  .container { padding: 0 8px; }
  .nav a { font-size: 11px; }
  .nav-list { padding: 0 10px; }
  .nav-list > li > a,
  .nav-list > li > .dropdown-toggle { padding: 0 12px; }
  .nav-list::-webkit-scrollbar { display: none; }
  .hero-content { max-width: 100%; }
  .hero-line2 {
    white-space: normal !important;
    overflow-wrap: anywhere;
    word-wrap: break-word;
    word-break: break-all;
    hyphens: auto;
    display: block;
    max-width: 100%;
  }
}