:root {
  --bg-dark: #07080d;
  --panel-bg: rgba(14, 17, 28, 0.82);
  --panel-border: rgba(94, 234, 212, 0.25);
  --accent: #2dd4bf;
  --accent-hot: #f43f5e;
  --text-main: #f1f5f9;
  --text-dim: #94a3b8;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', ui-monospace, monospace;
  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  user-select: none;
  -webkit-user-select: none;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--font-sans);
  touch-action: none;
}

#gpu-canvas {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
  cursor: crosshair;
}

/* Top Telemetry Header */
.hud-top {
  position: fixed;
  top: 12px;
  left: 12px;
  right: 12px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  pointer-events: none;
  z-index: 10;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--panel-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--panel-border);
  padding: 6px 12px;
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.45);
}

.brand-badge {
  background: linear-gradient(135deg, #2dd4bf, #3b82f6);
  color: #041014;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  padding: 3px 7px;
  border-radius: 4px;
}

.brand-sub {
  font-size: 0.78rem;
  color: var(--text-dim);
  font-weight: 500;
}

.stats-strip {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.stat-pill {
  background: var(--panel-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 8px;
  padding: 5px 10px;
  display: flex;
  flex-direction: column;
  min-width: 72px;
}

.stat-label {
  font-size: 0.62rem;
  font-family: var(--font-mono);
  color: var(--text-dim);
  letter-spacing: 0.06em;
}

.stat-value {
  font-size: 0.86rem;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--accent);
}

/* Control Panel */
.hud-panel {
  position: fixed;
  bottom: 16px;
  left: 16px;
  width: 330px;
  max-width: calc(100vw - 32px);
  background: var(--panel-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.6);
  z-index: 20;
  overflow: hidden;
  transition: transform 0.2s ease;
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(255, 255, 255, 0.03);
}

.panel-header h2 {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  color: var(--accent);
}

.icon-btn {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--text-main);
  width: 24px;
  height: 24px;
  border-radius: 5px;
  cursor: pointer;
  font-family: var(--font-mono);
  font-weight: bold;
  line-height: 1;
}

.panel-body {
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.panel-body.collapsed {
  display: none;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.control-group label {
  font-size: 0.72rem;
  color: var(--text-dim);
  font-weight: 500;
}

.control-group select {
  background: rgba(6, 9, 16, 0.9);
  color: var(--text-main);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 6px;
  padding: 6px 8px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  outline: none;
  cursor: pointer;
}

.control-group select:focus {
  border-color: var(--accent);
}

.control-row {
  display: flex;
  justify-content: space-between;
  gap: 8px;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.76rem;
  color: var(--text-main);
  cursor: pointer;
  flex: 1;
}

.checkbox-label input {
  accent-color: var(--accent);
  width: 15px;
  height: 15px;
  cursor: pointer;
}

.button-row {
  display: flex;
  gap: 8px;
}

.action-btn {
  flex: 1;
  padding: 8px 10px;
  border-radius: 7px;
  border: 1px solid rgba(255, 255, 255, 0.16);
  background: rgba(255, 255, 255, 0.07);
  color: var(--text-main);
  font-size: 0.76rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.action-btn:hover {
  background: rgba(255, 255, 255, 0.14);
  border-color: var(--accent);
}

.action-btn:active {
  transform: scale(0.97);
}

.action-btn.primary {
  background: linear-gradient(135deg, rgba(244, 63, 94, 0.85), rgba(249, 115, 22, 0.85));
  border-color: rgba(251, 113, 133, 0.5);
  color: #fff;
}

.action-btn.primary:hover {
  filter: brightness(1.12);
}

.action-btn.secondary {
  background: rgba(45, 212, 191, 0.12);
  border-color: rgba(45, 212, 191, 0.35);
  color: var(--accent);
}

.help-box {
  margin-top: 2px;
  padding-top: 8px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  font-size: 0.7rem;
  color: var(--text-dim);
  line-height: 1.45;
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.help-box strong {
  color: var(--text-main);
}

.arch-note {
  margin-top: 2px;
  color: #64748b;
  font-size: 0.66rem;
}

.arch-note code {
  color: var(--accent);
  font-family: var(--font-mono);
}

/* Error Modal */
.error-modal {
  position: fixed;
  inset: 0;
  background: rgba(5, 7, 12, 0.92);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  z-index: 100;
}

.error-modal[hidden] {
  display: none;
}

.error-card {
  max-width: 440px;
  background: #111827;
  border: 1px solid var(--accent-hot);
  padding: 24px;
  border-radius: 12px;
  text-align: center;
}

.error-card h2 {
  color: var(--accent-hot);
  margin-bottom: 10px;
}

.error-card p {
  color: var(--text-dim);
  font-size: 0.9rem;
  line-height: 1.5;
}

@media (max-width: 640px) {
  .brand-sub {
    display: none;
  }
  .stat-pill {
    min-width: 58px;
    padding: 4px 7px;
  }
  .stat-value {
    font-size: 0.75rem;
  }
  .hud-panel {
    bottom: 10px;
    left: 10px;
    right: 10px;
    width: auto;
  }
}