/* =========================================================================
   Visualizing the Riemann Hypothesis — UI styling
   ========================================================================= */

:root {
  --bg: #05060a;
  --panel: rgba(14, 18, 30, 0.72);
  --panel-border: rgba(120, 160, 220, 0.18);
  --text: #e8ecf4;
  --muted: #8a93a8;
  --accent: #3fe0ff;
  --gold: #ffcf5c;
  --green: #33d6a6;
  --magenta: #ff5cc8;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --mono: "SF Mono", "JetBrains Mono", "Fira Code", ui-monospace, Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
}

#scene {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
}

/* ---------- Loading overlay ---------- */
#loading {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 18px;
  background: radial-gradient(circle at 50% 40%, #0a0f1c 0%, #05060a 70%);
  z-index: 50;
  transition: opacity 0.8s ease;
}
#loading.hidden { opacity: 0; pointer-events: none; }
.spinner {
  width: 46px;
  height: 46px;
  border: 3px solid rgba(63, 224, 255, 0.18);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.9s linear infinite;
}
.loading-text { color: var(--muted); font-family: var(--mono); font-size: 13px; letter-spacing: 0.04em; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ---------- HUD (title) ---------- */
#hud {
  position: fixed;
  top: 22px;
  left: 26px;
  z-index: 20;
  pointer-events: none;
  max-width: min(46vw, 560px);
  text-shadow: 0 2px 18px rgba(0, 0, 0, 0.8);
}
#hud h1 {
  margin: 0;
  font-size: clamp(17px, 2.3vw, 27px);
  font-weight: 600;
  letter-spacing: 0.01em;
  background: linear-gradient(90deg, #ffffff, var(--accent) 60%, var(--gold));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
#hud .sub {
  margin: 6px 0 0;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  letter-spacing: 0.02em;
}

/* ---------- Nav ---------- */
#nav {
  position: fixed;
  left: 26px;
  bottom: 24px;
  z-index: 20;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  max-width: 60vw;
}
.nav-btn {
  appearance: none;
  border: 1px solid var(--panel-border);
  background: var(--panel);
  color: var(--muted);
  font-family: var(--mono);
  font-size: 12.5px;
  letter-spacing: 0.02em;
  padding: 9px 14px;
  border-radius: 10px;
  cursor: pointer;
  backdrop-filter: blur(8px);
  transition: all 0.18s ease;
}
.nav-btn:hover { color: var(--text); border-color: rgba(63, 224, 255, 0.45); transform: translateY(-1px); }
.nav-btn.active {
  color: #04121a;
  background: linear-gradient(120deg, var(--accent), #7ea8ff);
  border-color: transparent;
  font-weight: 600;
  box-shadow: 0 4px 22px rgba(63, 224, 255, 0.35);
}

/* ---------- Info panel ---------- */
#info {
  position: fixed;
  top: 90px;
  right: 22px;
  z-index: 20;
  width: min(340px, 38vw);
  max-height: calc(100vh - 180px);
  overflow: hidden;
  background: var(--panel);
  border: 1px solid var(--panel-border);
  border-radius: 14px;
  padding: 16px 18px;
  backdrop-filter: blur(10px);
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.45);
  transition: transform 0.3s ease, opacity 0.3s ease;
}
#info.collapsed { transform: translateX(calc(100% + 30px)); opacity: 0; }
.info-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 10px;
  letter-spacing: 0.01em;
}
.info-body { font-size: 13px; line-height: 1.55; color: var(--muted); overflow-y: auto; max-height: calc(100vh - 240px); }
.info-body p { margin: 0 0 10px; }
.info-body strong { color: var(--text); }
.info-body .stat { color: var(--accent); font-family: var(--mono); }
.info-body .stat.gold { color: var(--gold); }
.info-body .stat.green { color: var(--green); }
.info-body ul { margin: 6px 0 10px; padding-left: 18px; }
.info-body li { margin-bottom: 5px; }
.info-body code { font-family: var(--mono); font-size: 12px; color: var(--gold); background: rgba(255, 207, 92, 0.08); padding: 1px 5px; border-radius: 4px; }
.info-body .cite { color: #6f7891; font-size: 11.5px; font-style: italic; }

.info-toggle {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 24px;
  height: 24px;
  border-radius: 7px;
  border: 1px solid var(--panel-border);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  font-size: 13px;
  line-height: 1;
}
.info-toggle:hover { color: var(--text); border-color: var(--accent); }

/* ---------- Footer ---------- */
#foot {
  position: fixed;
  bottom: 26px;
  right: 24px;
  z-index: 20;
  display: flex;
  gap: 16px;
  align-items: center;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--muted);
  pointer-events: none; /* let clicks pass through to nav behind it */
  max-width: 38vw;
  justify-content: flex-end;
  text-align: right;
}
#foot a { pointer-events: auto; }
#foot a { color: var(--accent); text-decoration: none; opacity: 0.8; }
#foot a:hover { opacity: 1; text-decoration: underline; }

/* ---------- Responsive ---------- */
@media (max-width: 720px) {
  #hud { max-width: 86vw; }
  #info { width: 80vw; top: auto; bottom: 90px; right: 10px; }
  #nav { max-width: 92vw; }
  #foot { display: none; }
}