* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --ink: #0b0c0e;
  --panel: rgba(19, 21, 25, 0.82);
  --panel-2: #1b1e24;
  --line: rgba(201, 164, 104, 0.28);
  --line-soft: rgba(236, 231, 220, 0.08);
  --brass: #c9a468;
  --brass-dim: #93764a;
  --ivory: #ece7dc;
  --muted: #8b8f96;
  --serif: "Cormorant Garamond", "Noto Serif SC", Georgia, serif;
  --mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}

html, body { height: 100%; overflow: hidden; background: var(--ink); }
body { font-family: var(--serif); color: var(--ivory); -webkit-font-smoothing: antialiased; }

#stage, #stage canvas { position: fixed; inset: 0; width: 100%; height: 100%; display: block; }

/* ---------- loader ---------- */
#loader {
  position: fixed; inset: 0; z-index: 60;
  background: var(--ink);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 14px; transition: opacity 0.9s ease;
}
#loader.hidden { opacity: 0; pointer-events: none; }
.loader-title { font-size: 44px; font-weight: 900; letter-spacing: 0.35em; text-indent: 0.35em; }
.loader-sub { font-family: var(--mono); font-size: 11px; letter-spacing: 0.55em; text-indent: 0.55em; color: var(--brass); }
.loader-line { width: 190px; height: 1px; background: rgba(236,231,220,0.12); margin-top: 18px; overflow: hidden; }
.loader-line span { display: block; height: 100%; width: 40%; background: var(--brass); animation: load 1.2s ease-in-out infinite; }
@keyframes load { 0% { transform: translateX(-100%);} 100% { transform: translateX(480%);} }

/* ---------- header ---------- */
#hud-top {
  position: fixed; top: 0; left: 0; right: 0; z-index: 20;
  display: flex; justify-content: space-between; align-items: flex-start;
  padding: 22px 28px; pointer-events: none;
}
.brand { display: flex; gap: 14px; align-items: center; }
.brand-gem {
  width: 12px; height: 12px; margin-top: 6px;
  background: var(--brass); transform: rotate(45deg);
  box-shadow: 0 0 14px rgba(201,164,104,0.65);
}
.brand-text h1 { font-size: 21px; font-weight: 900; letter-spacing: 0.28em; }
.brand-text p { font-family: var(--mono); font-size: 9.5px; letter-spacing: 0.3em; color: var(--brass-dim); margin-top: 4px; }
.hud-actions { display: flex; gap: 10px; pointer-events: auto; }
.hud-btn {
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.12em;
  color: var(--brass); background: rgba(19,21,25,0.7);
  border: 1px solid var(--line); border-radius: 999px;
  padding: 9px 16px; cursor: pointer; backdrop-filter: blur(10px);
  transition: all 0.25s ease;
}
.hud-btn:hover { background: var(--brass); color: var(--ink); border-color: var(--brass); }

/* ---------- exhibit chips ---------- */
#chips {
  position: fixed; bottom: 22px; left: 50%; transform: translateX(-50%); z-index: 20;
  display: flex; gap: 6px; padding: 8px;
  background: var(--panel); border: 1px solid var(--line); border-radius: 999px;
  backdrop-filter: blur(14px); max-width: 94vw; overflow-x: auto;
}
.chip {
  display: flex; align-items: center; gap: 8px; white-space: nowrap;
  font-family: var(--serif); font-size: 14.5px; letter-spacing: 0.12em;
  color: var(--muted); background: transparent;
  border: 1px solid transparent; border-radius: 999px;
  padding: 8px 15px; cursor: pointer; transition: all 0.25s ease;
}
.chip b { font-family: var(--mono); font-size: 9.5px; font-weight: 500; color: var(--brass-dim); letter-spacing: 0.05em; }
.chip:hover { color: var(--ivory); }
.chip.active { background: var(--brass); color: var(--ink); border-color: var(--brass); }
.chip.active b { color: rgba(11,12,14,0.6); }

/* ---------- info panel ---------- */
#panel {
  position: fixed; top: 86px; right: 24px; bottom: 24px; width: 352px; z-index: 19;
  background: linear-gradient(180deg, rgba(23,25,30,0.9), rgba(15,17,20,0.94));
  border: 1px solid var(--line); border-radius: 14px;
  backdrop-filter: blur(16px);
  padding: 26px 24px 22px; overflow-y: auto;
  transform: translateX(calc(100% + 40px)); opacity: 0;
  transition: transform 0.55s cubic-bezier(0.22,1,0.3,1), opacity 0.4s ease;
}
#panel.open { transform: translateX(0); opacity: 1; }
#panel::-webkit-scrollbar { width: 4px; }
#panel::-webkit-scrollbar-thumb { background: var(--brass-dim); border-radius: 2px; }
#panel-close {
  position: absolute; top: 12px; right: 14px;
  width: 30px; height: 30px; border-radius: 50%;
  background: transparent; border: 1px solid var(--line-soft);
  color: var(--muted); font-size: 16px; cursor: pointer; transition: all 0.2s;
}
#panel-close:hover { color: var(--ink); background: var(--brass); border-color: var(--brass); }
.p-index { font-size: 62px; font-weight: 600; line-height: 0.95; color: var(--brass); font-style: italic; }
.p-title { font-size: 30px; font-weight: 900; letter-spacing: 0.14em; margin-top: 6px; }
.p-en { font-family: var(--mono); font-size: 10px; letter-spacing: 0.3em; color: var(--brass); margin-top: 6px; }
.p-desc { font-size: 14.5px; line-height: 1.85; color: rgba(236,231,220,0.82); margin-top: 16px; }
.p-formula {
  font-family: var(--mono); font-size: 13.5px; color: var(--ivory);
  background: rgba(201,164,104,0.08); border-left: 2px solid var(--brass);
  padding: 11px 14px; border-radius: 0 6px 6px 0; margin-top: 16px; letter-spacing: 0.04em;
}
.p-section {
  display: flex; align-items: center; gap: 12px;
  font-family: var(--mono); font-size: 10px; letter-spacing: 0.3em; color: var(--brass-dim);
  margin: 22px 0 12px;
}
.p-section-line { flex: 1; height: 1px; background: var(--line-soft); }
.p-readouts { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; }
.ro { background: var(--panel-2); border: 1px solid var(--line-soft); border-radius: 8px; padding: 9px 12px; }
.ro-l { display: block; font-family: var(--mono); font-size: 9px; letter-spacing: 0.2em; color: var(--muted); text-transform: uppercase; }
.ro-v { display: block; font-family: var(--mono); font-size: 16px; color: var(--ivory); margin-top: 4px; }
.ro-v em { font-style: normal; font-size: 10px; color: var(--brass-dim); margin-left: 3px; }

.ctl { margin-bottom: 14px; }
.ctl-head { display: flex; justify-content: space-between; font-size: 13px; letter-spacing: 0.1em; margin-bottom: 7px; }
.ctl-head .ctl-val { font-family: var(--mono); font-size: 12px; color: var(--brass); }
input[type="range"] {
  -webkit-appearance: none; appearance: none; width: 100%; height: 2px;
  background: rgba(236,231,220,0.16); border-radius: 1px; outline: none; cursor: pointer;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none; width: 15px; height: 15px; border-radius: 50%;
  background: var(--brass); border: 2px solid var(--ink);
  box-shadow: 0 0 10px rgba(201,164,104,0.5); cursor: grab;
}
input[type="range"]::-moz-range-thumb {
  width: 13px; height: 13px; border-radius: 50%;
  background: var(--brass); border: 2px solid var(--ink); cursor: grab;
}
.btn-row { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 14px; }
.pill-btn {
  font-family: var(--serif); font-size: 12.5px; letter-spacing: 0.14em;
  color: var(--brass); background: transparent;
  border: 1px solid var(--brass-dim); border-radius: 999px;
  padding: 7px 15px; cursor: pointer; transition: all 0.22s ease;
}
.pill-btn:hover { background: var(--brass); color: var(--ink); border-color: var(--brass); }
.pill-btn.on { background: var(--brass); color: var(--ink); border-color: var(--brass); }

/* ---------- hint & toast ---------- */
#hint {
  position: fixed; left: 28px; bottom: 26px; z-index: 18;
  font-family: var(--mono); font-size: 10px; letter-spacing: 0.18em; color: rgba(139,143,150,0.75);
  pointer-events: none;
}
#toast {
  position: fixed; top: 84px; left: 50%; transform: translate(-50%, -8px); z-index: 30;
  font-family: var(--mono); font-size: 11.5px; letter-spacing: 0.2em;
  color: var(--ink); background: var(--brass);
  padding: 9px 20px; border-radius: 999px;
  opacity: 0; transition: all 0.35s ease; pointer-events: none;
  box-shadow: 0 6px 30px rgba(201,164,104,0.35);
}
#toast.show { opacity: 1; transform: translate(-50%, 0); }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  #hud-top { padding: 14px 16px; }
  .brand-text p { display: none; }
  .brand-text h1 { font-size: 17px; }
  #panel {
    top: auto; left: 12px; right: 12px; bottom: 78px; width: auto;
    max-height: 44vh; transform: translateY(calc(100% + 100px));
  }
  #panel.open { transform: translateY(0); }
  #chips { bottom: 12px; }
  .chip { font-size: 13px; padding: 7px 12px; }
  #hint { display: none; }
  .p-index { font-size: 44px; }
}