:root {
  --whut-blue: #004b87;
  --whut-blue-deep: #00345f;
  --whut-blue-soft: #eaf3fa;
  --whut-red: #c82432;
  --whut-gold: #d9a441;
  --whut-ink: #152535;
  --whut-muted: #647688;
  --whut-line: rgba(0, 75, 135, .15);
  --ink: #ffffff;
  --ink-soft: rgba(0, 52, 95, .92);
  --paper: #ffffff;
  --paper-dim: #f4f7fa;
  --vermilion: var(--whut-blue);
  --vermilion-deep: var(--whut-blue-deep);
  --gold: var(--whut-red);
  --gold-soft: rgba(200, 36, 50, .28);
  --hair: var(--whut-line);
  --txt: var(--whut-ink);
  --txt-dim: var(--whut-muted);
  --serif: "STZhongsong", "Noto Serif SC", "Source Han Serif SC", "SimSun", serif;
  --sans: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
}

html, body { background: #eef3f7; }
#viewer { background: linear-gradient(145deg, #eaf1f6 0%, #f8fbfd 100%); }

/* Institutional portal-style viewer chrome */
#topbar {
  height: 64px;
  padding: 4px 20px 0;
  gap: 14px;
  color: var(--whut-ink);
  background: rgba(255, 255, 255, .94);
  border-bottom: 1px solid rgba(0, 75, 135, .16);
  box-shadow: 0 8px 28px rgba(16, 44, 68, .10);
  backdrop-filter: blur(18px) saturate(135%);
  -webkit-backdrop-filter: blur(18px) saturate(135%);
  animation: whutTopbarIn .55s cubic-bezier(.2,.75,.2,1) both;
}
#topbar::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--whut-blue) 0 72%, var(--whut-red) 72% 83%, var(--whut-gold) 83% 100%);
}
#btn-home {
  color: var(--whut-blue);
  border-color: rgba(0, 75, 135, .24);
  background: rgba(0, 75, 135, .04);
  border-radius: 4px;
  font-weight: 600;
}
#btn-home:hover { border-color: var(--whut-blue); color: var(--whut-blue-deep); background: var(--whut-blue-soft); }
#topbar .vline { height: 26px; background: rgba(0, 75, 135, .18); }
#topbar .title-wrap { align-items: center; gap: 10px; }
#topbar .title-wrap::before {
  content: "";
  display: block;
  width: 176px;
  height: 36px;
  flex: 0 0 176px;
  background: var(--whut-blue-deep) url('./whut-emblem.png') center / 164px auto no-repeat;
  border-radius: 2px;
}
#topbar .title {
  color: var(--whut-blue-deep);
  font-family: var(--sans);
  font-size: 18px;
  letter-spacing: 2px;
}
#topbar .subtitle { color: var(--whut-muted); letter-spacing: 1.1px; }
.tbtn {
  color: var(--whut-blue-deep);
  border-color: rgba(0, 75, 135, .22);
  background: #fff;
  border-radius: 4px;
  font-weight: 600;
}
.tbtn:hover { color: var(--whut-blue); border-color: var(--whut-blue); background: var(--whut-blue-soft); }
.tbtn.accent { color: #fff; background: var(--whut-blue); border-color: var(--whut-blue); box-shadow: 0 6px 16px rgba(0, 75, 135, .18); }
.tbtn.accent:hover { color: #fff; background: var(--whut-blue-deep); border-color: var(--whut-blue-deep); }
.tbtn.on { color: #fff; background: var(--whut-red); border-color: var(--whut-red); }

#panel {
  top: 82px;
  right: 18px;
  background: rgba(255, 255, 255, .96);
  border: 1px solid rgba(0, 75, 135, .16);
  border-radius: 4px;
  box-shadow: 0 18px 48px rgba(20, 49, 74, .16);
  animation: whutPanelIn .65s .12s cubic-bezier(.2,.75,.2,1) both;
}
.panel-head {
  min-height: 48px;
  background: linear-gradient(90deg, var(--whut-blue-deep), var(--whut-blue));
  border-bottom: 0;
}
.panel-title { color: #fff; font-family: var(--sans); letter-spacing: 2px; }
.panel-count { color: #fff; border-color: rgba(255,255,255,.45); background: rgba(255,255,255,.12); }
#panel-toggle { color: rgba(255,255,255,.82); }
#panel .hint { color: var(--whut-muted); background: #f5f8fb; padding: 10px 14px; }
.exhibit-item { border-top-color: rgba(0,75,135,.10); color: var(--whut-ink); }
.exhibit-item:hover { background: var(--whut-blue-soft); }
.exhibit-item .num { color: var(--whut-blue); }
.exhibit-item .eye { color: var(--whut-muted); }

.marker .pin {
  border-color: #fff;
  outline-color: rgba(0, 75, 135, .42);
  box-shadow: 0 5px 16px rgba(0, 52, 95, .30);
  animation: whutMarkerPulse 2.4s ease-in-out infinite;
}
.marker .tag {
  color: var(--whut-blue-deep);
  background: rgba(255, 255, 255, .94);
  border-color: rgba(0, 75, 135, .18);
  box-shadow: 0 6px 18px rgba(18, 49, 74, .14);
}

#card {
  background: rgba(255,255,255,.97);
  border-color: rgba(0,75,135,.18);
  border-top: 4px solid var(--whut-blue);
  border-radius: 4px;
  box-shadow: 0 20px 54px rgba(19, 48, 72, .22);
}
#card h2 { color: var(--whut-blue-deep); font-family: var(--sans); }
#card .era { background: var(--whut-red); color: #fff; border-radius: 2px; }
#card .rule { background: rgba(0,75,135,.15); }
#card .info { color: #3e5060; }
#card .abtn { color: var(--whut-blue); border-color: var(--whut-blue); }
#card .abtn:hover { background: var(--whut-blue-soft); }

#tourbar,
#stream-progress {
  color: #fff;
  background: rgba(0, 52, 95, .94);
  border-color: rgba(255,255,255,.16);
  box-shadow: 0 12px 34px rgba(0, 35, 65, .28);
}
#hintbar {
  color: #fff;
  background: rgba(0, 52, 95, .84);
  border-color: rgba(255,255,255,.15);
}
#stream-progress .track { background: rgba(255,255,255,.18); }
#stream-progress .track i { background: linear-gradient(90deg, #59aee9, #fff, var(--whut-red)); }

#editbox,
#help {
  background: rgba(255,255,255,.98);
  border-color: rgba(0,75,135,.22);
  border-top-color: var(--whut-blue);
  border-radius: 4px;
}
#editbox h4,
#help h3 { color: var(--whut-blue-deep); font-family: var(--sans); }
#editbox .sec { border-color: rgba(0,75,135,.12); }
#editbox .sec-title { color: var(--whut-blue); }
.ebtn { background: #f4f8fb; color: var(--whut-ink); border-color: rgba(0,75,135,.2); border-radius: 3px; }
.ebtn:hover { border-color: var(--whut-blue); background: var(--whut-blue-soft); }
.ebtn.primary { color: #fff; background: var(--whut-blue); border-color: var(--whut-blue); }

/* Branded loading lobby */
#loading {
  overflow: hidden;
  color: #fff;
  background: var(--whut-blue-deep);
}
#loading::before {
  display: none;
}
#loading::after {
  content: "";
  position: absolute;
  left: 28px;
  top: 22px;
  width: 245px;
  height: 50px;
  background: url('./whut-emblem.png') left center / contain no-repeat;
}
#loading .frame {
  z-index: 1;
  width: min(620px, 88vw);
  padding: 46px 54px 38px;
  text-align: left;
  border: 1px solid rgba(255,255,255,.28);
  border-left: 5px solid var(--whut-red);
  background: rgba(0, 34, 65, .46);
  box-shadow: 0 28px 70px rgba(0, 22, 42, .34);
  backdrop-filter: blur(14px);
  animation: whutLoaderIn .7s cubic-bezier(.16,.82,.2,1) both;
}
#loading .frame::before { inset: 8px; border-color: rgba(255,255,255,.08); }
#loading .big {
  color: #fff;
  font-family: var(--sans);
  font-size: clamp(34px, 5vw, 52px);
  font-weight: 700;
  letter-spacing: 7px;
  text-indent: 0;
}
#loading .seal {
  color: var(--whut-blue-deep);
  background: #fff;
  border-radius: 2px;
  box-shadow: none;
  font-family: var(--sans);
  font-weight: 700;
  letter-spacing: 3px;
}
#loading .intro { color: rgba(255,255,255,.72); }
#loading .bar { height: 5px; background: rgba(255,255,255,.16); }
#loading .bar i { background: linear-gradient(90deg, #fff, #79c5f4 70%, var(--whut-red)); box-shadow: 0 0 16px rgba(255,255,255,.36); }
#loading .small { color: rgba(255,255,255,.68); }
#loading .percent { color: #fff; font-weight: 700; }
#loading .tip { position: relative; z-index: 1; color: rgba(255,255,255,.55); }

@keyframes whutTopbarIn {
  from { opacity: 0; transform: translateY(-18px); }
  to { opacity: 1; transform: none; }
}
@keyframes whutPanelIn {
  from { opacity: 0; transform: translateX(22px); }
  to { opacity: 1; transform: none; }
}
@keyframes whutLoaderIn {
  from { opacity: 0; transform: translateY(22px) scale(.985); }
  to { opacity: 1; transform: none; }
}
@keyframes whutMarkerPulse {
  0%, 100% { box-shadow: 0 5px 16px rgba(0,52,95,.30), 0 0 0 0 rgba(0,75,135,.20); }
  50% { box-shadow: 0 5px 16px rgba(0,52,95,.30), 0 0 0 8px rgba(0,75,135,0); }
}
@media (max-width: 720px) {
  #topbar { height: 60px; padding: 4px 10px 0; gap: 7px; }
  #topbar .title-wrap::before { display: none; }
  #topbar .title { font-size: 16px; letter-spacing: 1px; }
  #panel { top: 72px; right: 10px; width: 208px; }
  #loading { padding: 18px; }
  #loading::after { left: 18px; top: 18px; width: 190px; height: 40px; }
  #loading .frame { width: 100%; padding: 38px 26px 30px; }
  #loading .big { font-size: 30px; letter-spacing: 4px; }
  #loading .intro { line-height: 1.85; }
}

@media (prefers-reduced-motion: reduce) {
  #topbar,
  #panel,
  #loading .frame,
  .marker .pin,
  #loading::before { animation: none !important; }
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; }
}