/* =====================================================================
 * GARGANTUA — UI styling for the Schwarzschild black-hole raytracer.
 * Visual language: deep space, faint cyan grid, warm emissive accents.
 * Layout: top HUD, right parameter panel, center cinematic intro.
 * ===================================================================== */

:root {
  --bg: #04060c;
  --bg2: #0a0d18;
  --fg: #d9e3f0;
  --fg-dim: #8a96a8;
  --accent: #ffc884;          /* warm emissive disk */
  --accent-2: #6cd6ff;        /* cool UI accent */
  --accent-dim: rgba(108, 214, 255, 0.45);
  --warn: #ff7a4d;
  --line: rgba(255, 255, 255, 0.07);
  --line-strong: rgba(255, 255, 255, 0.14);
  --panel-bg: rgba(8, 11, 22, 0.78);
  --panel-bg-strong: rgba(8, 11, 22, 0.93);
  --shadow: 0 14px 48px rgba(0, 0, 0, 0.55);
  --r-sm: 6px;
  --r-md: 10px;
  --r-lg: 14px;
  --t-fast: 160ms cubic-bezier(.4,.1,.2,1);
  --t-med: 280ms cubic-bezier(.4,.1,.2,1);
}

* { box-sizing: border-box; }

html, body {
  margin: 0; padding: 0;
  width: 100%; height: 100%;
  background: #000;
  color: var(--fg);
  font: 12px/1.4 'Inter', 'Segoe UI', system-ui, -apple-system, 'Helvetica Neue', sans-serif;
  overflow: hidden;
  overscroll-behavior: none;
  -webkit-font-smoothing: antialiased;
}

body.boot { cursor: wait; }
body.ready { cursor: default; }

#gl {
  position: fixed; inset: 0;
  width: 100%; height: 100%;
  display: block;
  background: #000;
  touch-action: none;
  outline: none;
}

/* ----------- HUD top ----------- */
.hud {
  position: fixed;
  pointer-events: none;
  z-index: 5;
  color: var(--fg);
  text-shadow: 0 0 12px rgba(0,0,0,.6);
}
.hud-top {
  top: 0; left: 0; right: 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  padding: 14px 22px;
  gap: 16px;
  background: linear-gradient(to bottom, rgba(0,0,0,.55), rgba(0,0,0,0));
}
.hud-title {
  display: flex; align-items: center; gap: 10px;
  font-weight: 600; letter-spacing: .18em;
}
.brand-mark { color: var(--accent); font-size: 10px; transform: translateY(-1px); }
.brand-text { font-size: 14px; }
.brand-sub { color: var(--fg-dim); letter-spacing: .25em; font-size: 10px; }
.hud-status {
  justify-self: center;
  display: flex; align-items: center; gap: 8px;
  font-size: 10px; letter-spacing: .25em; color: var(--fg-dim);
  text-transform: uppercase;
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(0,0,0,.25);
  backdrop-filter: blur(6px);
}
.hud-status .dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--accent-2);
  box-shadow: 0 0 8px var(--accent-2);
  animation: pulse 1.4s ease-in-out infinite;
}
.hud-status.bad .dot { background: var(--warn); box-shadow: 0 0 8px var(--warn); }
@keyframes pulse {
  0%, 100% { opacity: .35; transform: scale(.85); }
  50%      { opacity: 1;   transform: scale(1); }
}
.hud-stats {
  justify-self: end;
  display: flex; gap: 12px;
  font-size: 10px; letter-spacing: .18em; color: var(--fg-dim);
}
.hud-stats span {
  padding: 4px 8px;
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  background: rgba(0,0,0,.25);
  backdrop-filter: blur(6px);
  font-variant-numeric: tabular-nums;
}

.hud.hidden { display: none; }

/* ----------- Cinematic intro ----------- */
.hud-cine {
  position: fixed; inset: 0;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  pointer-events: none;
  text-align: center;
  z-index: 4;
  transition: opacity 800ms ease, transform 800ms ease;
  opacity: 0;
}
.hud-cine.show {
  opacity: 1;
  transform: translateY(0);
}
.hud-cine.hide {
  opacity: 0;
  transform: translateY(20px);
}
.cine-eyebrow {
  letter-spacing: .45em; font-size: 11px; color: var(--fg-dim);
  margin-bottom: 14px;
}
.cine-title {
  font-size: clamp(48px, 9vw, 124px);
  letter-spacing: .25em; font-weight: 200; margin: 0;
  background: linear-gradient(180deg, #fff 0%, #ffd1a0 60%, #ff8a4d 100%);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 30px rgba(255, 140, 60, .35));
}
.cine-sub {
  margin-top: 18px; color: var(--fg-dim);
  letter-spacing: .25em; font-size: 12px;
}

/* ----------- Crosshair ----------- */
.hud-cross {
  position: fixed; left: 50%; top: 50%;
  transform: translate(-50%, -50%);
  width: 40px; height: 40px;
  color: rgba(255, 200, 132, .55);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-med);
}
.hud-cross.show { opacity: 1; }
.hud-cross svg { width: 100%; height: 100%; }

/* ----------- Parameter panel ----------- */
.panel {
  position: fixed; top: 14px; right: 14px;
  width: 308px; max-height: calc(100vh - 28px);
  background: var(--panel-bg);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px) saturate(120%);
  z-index: 6;
  display: flex; flex-direction: column;
  font-size: 11px;
  letter-spacing: .04em;
  transition: width var(--t-med), height var(--t-med), opacity var(--t-med);
  overflow: hidden;
}
.panel.collapsed { width: 44px; }
.panel.collapsed .panel-body,
.panel.collapsed .panel-title { display: none; }
.panel.collapsed .panel-head { justify-content: center; padding: 12px 0; }

.panel-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
  flex-shrink: 0;
}
.panel-title {
  font-size: 10px; letter-spacing: .35em; color: var(--fg-dim);
  font-weight: 600;
}
.panel-toggle {
  background: transparent; color: var(--fg);
  border: 1px solid var(--line);
  width: 22px; height: 22px;
  border-radius: var(--r-sm);
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  font-size: 14px;
  transition: background var(--t-fast);
}
.panel-toggle:hover { background: rgba(255,255,255,.06); }

.panel-body {
  padding: 12px 14px 16px;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--line-strong) transparent;
}
.panel-body::-webkit-scrollbar { width: 6px; }
.panel-body::-webkit-scrollbar-thumb { background: var(--line-strong); border-radius: 4px; }

.panel-group { margin-bottom: 14px; }
.panel-group-title {
  font-size: 9px; letter-spacing: .35em; color: var(--accent-2);
  margin-bottom: 8px; opacity: .85;
}

.row { display: flex; gap: 6px; align-items: center; }
.row.btnrow { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 6px; }
#debug-grid { grid-template-columns: repeat(2, 1fr); }

.param { margin-bottom: 8px; }
.param label {
  display: flex; justify-content: space-between; align-items: center;
  font-size: 11px; color: var(--fg);
  margin-bottom: 4px;
}
.param label em {
  font-style: normal; color: var(--accent);
  font-size: 10px;
  font-variant-numeric: tabular-nums;
  background: rgba(255, 200, 132, .08);
  padding: 1px 6px;
  border-radius: 4px;
  letter-spacing: .05em;
}

/* Slider styling — cross-browser */
input[type=range] {
  -webkit-appearance: none; appearance: none;
  width: 100%; height: 18px;
  background: transparent; cursor: pointer;
}
input[type=range]::-webkit-slider-runnable-track {
  height: 3px;
  background: linear-gradient(to right, var(--accent-2) 0%, var(--accent-2) var(--p, 50%), rgba(255,255,255,.08) var(--p, 50%));
  border-radius: 2px;
}
input[type=range]::-moz-range-track {
  height: 3px;
  background: rgba(255,255,255,.08);
  border-radius: 2px;
}
input[type=range]::-moz-range-progress {
  height: 3px;
  background: var(--accent-2);
  border-radius: 2px;
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none;
  width: 12px; height: 12px; border-radius: 50%;
  background: #fff;
  border: 1px solid var(--accent-2);
  box-shadow: 0 0 6px var(--accent-dim);
  margin-top: -4.5px;
  cursor: grab;
}
input[type=range]::-webkit-slider-thumb:active { cursor: grabbing; }
input[type=range]::-moz-range-thumb {
  width: 12px; height: 12px; border-radius: 50%;
  background: #fff; border: 1px solid var(--accent-2);
  cursor: grab;
}

.ctrl-select {
  width: 100%;
  background: rgba(0,0,0,.4);
  color: var(--fg);
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  padding: 6px 8px;
  font-size: 11px;
  letter-spacing: .08em;
  cursor: pointer;
}
.ctrl-select:focus { outline: none; border-color: var(--accent-2); }

.btn {
  background: rgba(255,255,255,.04);
  border: 1px solid var(--line);
  color: var(--fg);
  border-radius: var(--r-sm);
  padding: 6px 4px;
  font-size: 10px;
  letter-spacing: .12em;
  cursor: pointer;
  text-transform: lowercase;
  transition: background var(--t-fast), border-color var(--t-fast), color var(--t-fast);
  font-family: inherit;
}
.btn:hover { background: rgba(255,255,255,.09); border-color: var(--line-strong); }
.btn.active {
  background: rgba(108, 214, 255, .14);
  border-color: var(--accent-2);
  color: var(--accent-2);
}
.qbtn.active { background: rgba(255, 200, 132, .14); border-color: var(--accent); color: var(--accent); }

.panel-help {
  margin-top: 10px; padding-top: 10px;
  border-top: 1px dashed var(--line);
  color: var(--fg-dim); font-size: 10px;
  letter-spacing: .04em;
  display: grid; gap: 4px;
}
.panel-help b { color: var(--accent-2); font-weight: 600; }

/* ----------- Splash ----------- */
.splash {
  position: fixed; inset: 0;
  background: radial-gradient(ellipse at center, #0c1226 0%, #02030a 70%);
  display: flex; align-items: center; justify-content: center;
  z-index: 30;
  transition: opacity 600ms ease;
}
.splash.gone { opacity: 0; pointer-events: none; }
.splash-inner { text-align: center; }
.splash-spin {
  width: 64px; height: 64px;
  margin: 0 auto 18px;
  border: 2px solid transparent;
  border-top-color: var(--accent);
  border-right-color: var(--accent-2);
  border-radius: 50%;
  animation: spin 1.4s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.splash-text {
  letter-spacing: .3em; font-size: 11px; color: var(--fg-dim);
  text-transform: uppercase;
}

/* ----------- Mobile ----------- */
@media (max-width: 720px) {
  .panel {
    width: calc(100vw - 22px); right: 11px; left: 11px;
    top: auto; bottom: 11px; max-height: 56vh;
  }
  .panel.collapsed { width: 130px; }
  .hud-top {
    grid-template-columns: 1fr auto;
    padding: 10px 14px;
  }
  .hud-stats { display: none; }
  .cine-title { font-size: clamp(40px, 14vw, 80px); }
}

@media (hover: none) and (pointer: coarse) {
  input[type=range]::-webkit-slider-thumb { width: 18px; height: 18px; }
}

/* ----------- Reduced motion ----------- */
@media (prefers-reduced-motion: reduce) {
  .hud-cine, .splash { transition: opacity 200ms ease; }
  .hud-status .dot { animation: none; opacity: 1; }
}