/* ===========================================================================
   GARGANTUA — Schwarzschild Black Hole Raytracer
   Full-screen HUD / overlay styling.  Pure CSS, no frameworks.
   =========================================================================== */

:root {
  --bg:        #04050a;
  --ink:       #e8eefc;
  --dim:       #8fa4c8;
  --dimmer:    #5d6f92;
  --amber:     #ffb03a;
  --amber-dim: #b97c22;
  --cyan:      #57e0ff;
  --line:      rgba(140, 175, 230, 0.16);
  --line-soft: rgba(140, 175, 230, 0.09);
  --glass:     rgba(8, 12, 22, 0.58);
  --glass-2:   rgba(8, 12, 22, 0.82);
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", "Cascadia Mono", Menlo, Consolas, monospace;
  --sans: system-ui, -apple-system, "Segoe UI", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
  -webkit-tap-highlight-color: transparent;
  overscroll-behavior: none;
}

body { touch-action: none; }

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

/* ===========================================================================
   HUD shell
   =========================================================================== */
.hud {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 10;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.02em;
  opacity: 0;
  transition: opacity 0.28s ease;
}
/* fade the whole HUD in once the first frame has been validated */
body.ready .hud { opacity: 1; }
.hud.hidden { opacity: 0; pointer-events: none !important; }
body.ready .hud.hidden { opacity: 0; }
.hud > * { pointer-events: auto; }

/* ---- title ---- */
.hud-title {
  position: absolute;
  top: max(18px, env(safe-area-inset-top));
  left: max(20px, env(safe-area-inset-left));
  padding: 0 0 0 12px;
  border-left: 2px solid var(--amber);
  text-shadow: 0 2px 18px rgba(0, 0, 0, 0.9);
}
.hud-title h1 {
  margin: 0;
  font-family: var(--sans);
  font-size: clamp(20px, 3.2vw, 34px);
  font-weight: 800;
  letter-spacing: 0.22em;
  line-height: 1;
  color: #fff;
  text-transform: uppercase;
}
.hud-title .sub {
  margin-top: 6px;
  font-size: clamp(8px, 1.05vw, 10.5px);
  letter-spacing: 0.26em;
  color: var(--amber);
  text-transform: uppercase;
}
.hud-title .phys {
  margin-top: 5px;
  font-size: 9.5px;
  color: var(--dimmer);
  letter-spacing: 0.04em;
}

/* ---- stats ---- */
.hud-stats {
  position: absolute;
  top: max(18px, env(safe-area-inset-top));
  right: max(20px, env(safe-area-inset-right));
  min-width: 178px;
  padding: 10px 12px;
  background: var(--glass);
  border: 1px solid var(--line);
  border-radius: 8px;
  backdrop-filter: blur(9px) saturate(120%);
  -webkit-backdrop-filter: blur(9px) saturate(120%);
  transition: opacity 0.2s ease;
}
.hud-stats.off { opacity: 0; pointer-events: none; }
.hud-stats .row { display: flex; justify-content: space-between; gap: 14px; line-height: 1.62; }
.hud-stats .row span { color: var(--dimmer); }
.hud-stats .row b { color: var(--cyan); font-weight: 600; font-variant-numeric: tabular-nums; }

/* ---- preset / quality / effect bars ---- */
.hud-presets, .hud-quality, .hud-effects {
  position: absolute;
  left: max(20px, env(safe-area-inset-left));
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  max-width: min(46vw, 470px);
}
.hud-presets { bottom: 108px; }
.hud-quality { bottom: 72px; }
.hud-effects { bottom: 40px; }

.chip, .qbtn, .fxbtn {
  appearance: none;
  font-family: var(--mono);
  color: var(--dim);
  background: var(--glass);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 5px 9px;
  font-size: 10.5px;
  line-height: 1.2;
  cursor: pointer;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: color 0.16s, border-color 0.16s, background 0.16s, transform 0.12s;
  white-space: nowrap;
}
.chip i, .qbtn i {
  font-style: normal;
  color: var(--amber-dim);
  margin-right: 5px;
  font-size: 9.5px;
}
.chip em { display: block; font-style: normal; font-size: 8px; letter-spacing: 0.14em; color: var(--dimmer); }
.chip:hover, .qbtn:hover, .fxbtn:hover { color: var(--ink); border-color: rgba(140, 175, 230, 0.4); }
.chip:active, .qbtn:active, .fxbtn:active { transform: translateY(1px); }
.chip.on, .qbtn.on, .fxbtn.on {
  color: #08090e;
  background: var(--amber);
  border-color: var(--amber);
}
.chip.on em, .chip.on i { color: rgba(8, 9, 14, 0.62); }
.chip.wide { padding-right: 12px; }
.qbtn { padding: 5px 12px; }
.fxbtn { padding: 4px 8px; font-size: 10px; }
.fxbtn.on { background: var(--cyan); border-color: var(--cyan); }

/* ---- parameter panel ---- */
.hud-panel {
  position: absolute;
  top: 0;
  right: 0;
  height: 100%;
  width: min(340px, 88vw);
  background: linear-gradient(180deg, rgba(6, 9, 18, 0.94), rgba(4, 6, 12, 0.97));
  border-left: 1px solid var(--line);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  transform: translateX(101%);
  transition: transform 0.32s cubic-bezier(0.22, 0.7, 0.2, 1);
  display: flex;
  flex-direction: column;
  z-index: 12;
  padding-top: env(safe-area-inset-top);
}
.hud-panel.open { transform: translateX(0); box-shadow: -24px 0 60px rgba(0, 0, 0, 0.6); }
.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 13px 14px;
  border-bottom: 1px solid var(--line);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--ink);
  text-transform: uppercase;
}
.panel-head b { color: var(--amber); font-weight: 600; }
.panel-head i { font-style: normal; color: var(--dimmer); margin-left: 6px; }
.panel-close {
  appearance: none;
  background: none;
  border: 1px solid var(--line);
  border-radius: 5px;
  color: var(--dim);
  width: 24px;
  height: 24px;
  font-size: 15px;
  line-height: 1;
  cursor: pointer;
}
.panel-close:hover { color: var(--ink); border-color: var(--amber); }

.panel-body { overflow-y: auto; overscroll-behavior: contain; padding: 8px 14px 28px; }
.panel-body::-webkit-scrollbar { width: 8px; }
.panel-body::-webkit-scrollbar-thumb { background: rgba(140, 175, 230, 0.22); border-radius: 4px; }

.group-title {
  margin: 16px 0 8px;
  padding-bottom: 5px;
  border-bottom: 1px dashed var(--line-soft);
  color: var(--amber);
  font-size: 10px;
  letter-spacing: 0.2em;
}
.group-title:first-child { margin-top: 6px; }

.prow { display: grid; grid-template-columns: 1fr 84px; gap: 4px 8px; margin-bottom: 9px; align-items: center; }
.prow label { grid-column: 1 / -1; display: flex; justify-content: space-between; align-items: baseline; gap: 8px; }
.prow label span { color: var(--ink); font-size: 11px; }
.prow label em { font-style: normal; color: var(--dimmer); font-size: 8.5px; letter-spacing: 0.08em; text-transform: uppercase; }
.prow .pval { color: var(--cyan); font-size: 10.5px; text-align: right; font-variant-numeric: tabular-nums; }

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 16px;
  background: transparent;
  cursor: ew-resize;
}
input[type="range"]::-webkit-slider-runnable-track {
  height: 3px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--amber-dim), rgba(140, 175, 230, 0.2));
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 12px;
  height: 12px;
  margin-top: -4.5px;
  border-radius: 50%;
  background: var(--amber);
  border: 2px solid #0a0d16;
  box-shadow: 0 0 10px rgba(255, 176, 58, 0.6);
}
input[type="range"]::-moz-range-track { height: 3px; border-radius: 2px; background: rgba(140, 175, 230, 0.25); }
input[type="range"]::-moz-range-thumb {
  width: 12px; height: 12px; border: 2px solid #0a0d16; border-radius: 50%;
  background: var(--amber); box-shadow: 0 0 10px rgba(255, 176, 58, 0.6);
}

/* ---- help ---- */
.hud-help {
  position: absolute;
  bottom: max(40px, env(safe-area-inset-bottom));
  right: max(20px, env(safe-area-inset-right));
  text-align: right;
  color: var(--dimmer);
  font-size: 9.5px;
  line-height: 1.85;
  text-shadow: 0 1px 10px #000;
}
.hud-help kbd {
  font-family: var(--mono);
  color: var(--ink);
  background: rgba(140, 175, 230, 0.12);
  border: 1px solid var(--line);
  border-radius: 3px;
  padding: 1px 5px;
  font-size: 9.5px;
}

/* ---- debug badge ---- */
.hud-debug {
  position: absolute;
  bottom: max(40px, env(safe-area-inset-bottom));
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: baseline;
  gap: 9px;
  padding: 7px 15px;
  background: var(--glass-2);
  border: 1px solid var(--line);
  border-radius: 20px;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  opacity: 0;
  transition: opacity 0.25s ease, border-color 0.25s;
  max-width: min(92vw, 640px);
}
.hud-debug.active { opacity: 1; border-color: rgba(255, 176, 58, 0.45); }
.hud-debug b {
  color: #08090e;
  background: var(--amber);
  border-radius: 4px;
  padding: 1px 7px;
  font-size: 11px;
}
.hud-debug span { color: var(--ink); font-size: 12px; }
.hud-debug em { font-style: normal; color: var(--amber); font-size: 9px; letter-spacing: 0.16em; }
.hud-debug i { font-style: normal; color: var(--dimmer); font-size: 9.5px; }

/* ---- toast ---- */
.hud-toast {
  position: absolute;
  bottom: 148px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}
.toast {
  padding: 7px 16px;
  background: var(--glass-2);
  border: 1px solid var(--line);
  border-radius: 18px;
  color: var(--ink);
  font-size: 11px;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.3s ease, transform 0.3s ease;
}
.toast.in { opacity: 1; transform: translateY(0); }

/* ===========================================================================
   Overlays
   =========================================================================== */
.overlay {
  position: fixed;
  inset: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: center;
  background: radial-gradient(circle at 50% 45%, #0a0f1c 0%, #04050a 62%, #000 100%);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.5s ease;
}
.overlay.show { opacity: 1; pointer-events: auto; }
.overlay .panel { text-align: center; max-width: min(560px, 86vw); padding: 24px; }
.overlay h2 {
  margin: 14px 0 8px;
  font-size: 15px;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: #fff;
}
.overlay p { margin: 0 0 8px; color: var(--dim); font-size: 12px; line-height: 1.7; }
.overlay small { display: block; color: var(--dimmer); font-size: 10px; letter-spacing: 0.06em; }
.overlay pre {
  margin: 10px 0 6px;
  padding: 10px;
  max-height: 30vh;
  overflow: auto;
  text-align: left;
  font-size: 10px;
  color: #ff9b8a;
  background: rgba(255, 90, 60, 0.06);
  border: 1px solid rgba(255, 90, 60, 0.2);
  border-radius: 6px;
  white-space: pre-wrap;
}
.overlay button {
  margin-top: 16px;
  appearance: none;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: #08090e;
  background: var(--amber);
  border: 0;
  border-radius: 6px;
  padding: 9px 20px;
  cursor: pointer;
}
.overlay button:hover { filter: brightness(1.12); }

/* animated accretion ring for the boot screen */
.ring { position: relative; width: 74px; height: 74px; margin: 0 auto; }
.ring i {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 2px solid transparent;
  border-top-color: var(--amber);
  animation: spin 1.5s linear infinite;
}
.ring i:nth-child(2) { inset: 9px; border-top-color: var(--cyan); animation-duration: 2.1s; animation-direction: reverse; }
.ring i:nth-child(3) { inset: 18px; border-top-color: rgba(255, 255, 255, 0.5); animation-duration: 2.9s; }
.ring.warn i { border-top-color: #ff7a5a; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ===========================================================================
   Responsive / mobile
   =========================================================================== */
@media (max-width: 900px), (max-height: 620px) {
  .hud { font-size: 10px; }
  .hud-stats { min-width: 142px; padding: 7px 9px; }
  .hud-stats .row { line-height: 1.5; }
  .hud-help { display: none; }
  .hud-presets { bottom: 96px; max-width: 78vw; }
  .hud-quality { bottom: 62px; }
  .hud-effects { bottom: 30px; max-width: 88vw; }
  .hud-debug { bottom: 132px; padding: 5px 10px; }
  .hud-debug i { display: none; }
  .hud-toast { bottom: 176px; }
  .hud-title .phys { display: none; }
  .chip em { display: none; }
  .hud-panel { width: 100vw; }
  .overlay p { font-size: 11px; }
}

@media (max-width: 520px) {
  .hud-title h1 { letter-spacing: 0.14em; }
  .hud-title .sub { letter-spacing: 0.16em; }
  .chip, .qbtn, .fxbtn { padding: 4px 7px; font-size: 9.5px; }
  .hud-effects { gap: 4px; }
  .hud-stats { min-width: 126px; }
  .hud-stats .row span { font-size: 9px; }
}

@media (prefers-reduced-motion: reduce) {
  .ring i { animation-duration: 6s; }
  .hud-panel { transition: none; }
}