:root {
  --bg-dark: #ffffff;
  --panel-bg: #ffffff;
  --accent-cyan: #0000ff; /* Stark brutalist blue */
  --accent-purple: #ff00ff; /* Stark brutalist magenta */
  --accent-green: #008800; /* Darker green for light-theme contrast */
  --border-light: #cccccc;
  --border-stark: #000000;
  --text-primary: #000000;
  --text-muted: #555555;
  --font-tech: 'Syne Mono', monospace;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  border-radius: 0 !important; /* Strict brutalist sharp corners */
}

body, html {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-dark);
  font-family: var(--font-tech);
  color: var(--text-primary);
  font-size: 13px;
  letter-spacing: 0.05em;
  user-select: none;
  -webkit-user-select: none;
}

/* Canvas Layers */
#gl-canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
}

#overlay-canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 2;
  pointer-events: none;
}

/* Stark Technical Landing Screen */
#intro-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--bg-dark);
  z-index: 10;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 20px;
  transition: opacity 0.5s steps(4, end), visibility 0.5s; /* Snappy transition */
}

#intro-overlay.fade-out {
  opacity: 0;
  visibility: hidden;
}

#start-btn {
  font-family: var(--font-tech);
  background: transparent;
  color: var(--text-primary);
  border: 3px solid var(--border-stark);
  padding: 16px 48px;
  font-size: 2.8rem;
  font-weight: bold;
  letter-spacing: 0.1em;
  cursor: pointer;
  transition: all 0.15s ease;
  outline: none;
  text-align: center;
}

#start-btn:hover {
  background: var(--border-stark);
  color: var(--bg-dark);
}

#start-btn:active {
  transform: translate(2px, 2px);
}

/* Spinner */
.spinner {
  width: 24px;
  height: 24px;
  border: 2px solid var(--border-light);
  border-left-color: var(--accent-cyan);
  animation: spin 0.8s linear infinite;
  margin-top: 20px;
  align-self: center;
}

.spinner.hidden {
  display: none;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.status-text {
  margin-top: 16px;
  font-size: 1.1rem;
  color: var(--accent-cyan);
  align-self: center;
  height: 24px;
  line-height: 24px;
  text-align: center;
}

/* HUD Toggle Button */
.hud-toggle-btn {
  position: absolute;
  top: 16px;
  right: 16px;
  background: var(--panel-bg);
  border: 1px solid var(--border-stark);
  padding: 8px 14px;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  z-index: 5;
  transition: all 0.15s ease;
}

.hud-toggle-btn .icon {
  font-size: 11px;
  font-weight: bold;
  color: var(--text-primary);
}

.hud-toggle-btn:hover {
  background: var(--border-stark);
}

.hud-toggle-btn:hover .icon {
  color: var(--bg-dark);
}

/* HUD Panel (Brutalist Technical) */
.glass-panel {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 300px;
  max-height: calc(100vh - 32px);
  background: var(--panel-bg);
  border: 2px solid var(--border-stark);
  box-shadow: 6px 6px 0px var(--border-stark);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 20px;
  z-index: 5;
  overflow-y: auto;
  opacity: 0;
  pointer-events: none;
  transform: translateY(-5px);
  transition: opacity 0.2s steps(3, end), transform 0.2s steps(3, end);
}

.glass-panel.show {
  opacity: 1;
  pointer-events: all;
  transform: translateY(0);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 2px solid var(--border-light);
  padding-bottom: 10px;
}

.panel-header h2 {
  font-size: 11px;
  font-weight: bold;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.close-btn {
  font-size: 18px;
  cursor: pointer;
  color: var(--text-muted);
  line-height: 1;
  transition: color 0.1s;
}

.close-btn:hover {
  color: var(--text-primary);
}

.panel-section {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.panel-section h3 {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--accent-cyan);
  font-weight: bold;
}

/* Mode Selection Grid */
.mode-select-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 6px;
}

.mode-btn {
  font-family: var(--font-tech);
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border-light);
  padding: 8px;
  font-size: 11px;
  cursor: pointer;
  text-align: center;
  transition: all 0.1s ease;
  outline: none;
}

.mode-btn:hover {
  color: var(--text-primary);
  border-color: var(--text-muted);
}

.mode-btn.active {
  background: var(--border-stark);
  border-color: var(--border-stark);
  color: var(--bg-dark);
  font-weight: bold;
}

/* Control groups and sliders */
.control-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.control-group label {
  font-size: 10px;
  display: flex;
  justify-content: space-between;
  text-transform: uppercase;
  color: var(--text-primary);
}

.val-display {
  font-family: var(--font-tech);
  color: var(--accent-cyan);
  font-weight: bold;
}

input[type=range] {
  -webkit-appearance: none;
  width: 100%;
  background: transparent;
  outline: none;
}

input[type=range]::-webkit-slider-runnable-track {
  width: 100%;
  height: 2px;
  background: var(--border-light);
}

input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  height: 12px;
  width: 12px;
  background: var(--text-primary);
  border: 1px solid var(--border-stark);
  cursor: pointer;
  margin-top: -5px;
  transition: background 0.1s;
}

input[type=range]::-webkit-slider-thumb:hover {
  background: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

/* Custom Checkbox Toggle */
.toggle-group {
  margin-bottom: 2px;
}

.toggle-container {
  display: flex;
  align-items: center;
  position: relative;
  padding-left: 24px;
  cursor: pointer;
  font-size: 11px;
  text-transform: uppercase;
  color: var(--text-primary);
  user-select: none;
}

.toggle-container input {
  position: absolute;
  opacity: 0;
  cursor: pointer;
  height: 0;
  width: 0;
}

.checkmark {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  left: 0;
  height: 12px;
  width: 12px;
  background-color: transparent;
  border: 1px solid var(--border-light);
  transition: all 0.1s ease;
}

.toggle-container:hover input ~ .checkmark {
  border-color: var(--text-muted);
}

.toggle-container input:checked ~ .checkmark {
  background-color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

.checkmark:after {
  content: "";
  position: absolute;
  display: none;
}

/* Panel Footer */
.panel-footer {
  display: flex;
  justify-content: space-between;
  font-size: 9px;
  text-transform: uppercase;
  color: var(--text-muted);
  border-top: 2px solid var(--border-light);
  padding-top: 10px;
}

#stats-fps, #stats-hands {
  font-family: var(--font-tech);
}

/* Scrollbar styles */
.glass-panel::-webkit-scrollbar {
  width: 4px;
}

.glass-panel::-webkit-scrollbar-track {
  background: transparent;
}

.glass-panel::-webkit-scrollbar-thumb {
  background: var(--border-light);
}

.glass-panel::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* Brutalist Color Picker Styling */
input[type=color] {
  -webkit-appearance: none;
  border: 1px solid var(--border-stark);
  background: none;
  width: 100%;
  height: 28px;
  cursor: pointer;
  padding: 0;
}
input[type=color]::-webkit-color-swatch-wrapper {
  padding: 0;
}
input[type=color]::-webkit-color-swatch {
  border: none;
}

/* Viewport Overlays (Bottom Corners) */
.viewport-overlay-item {
  position: absolute;
  bottom: 16px;
  z-index: 4; /* Layer between gl-canvas and HUD panel */
  font-family: var(--font-tech);
  font-size: 11px;
  text-transform: lowercase;
  color: var(--text-primary);
  background: var(--panel-bg);
  border: 1px solid var(--border-stark);
  padding: 6px 12px;
  pointer-events: all;
  text-decoration: none;
  font-weight: bold;
}

.viewport-overlay-item.bottom-left {
  left: 16px;
}

.viewport-overlay-item.bottom-right {
  right: 16px;
  cursor: pointer;
  transition: all 0.15s ease;
}

.viewport-overlay-item.bottom-right:hover {
  background: var(--border-stark);
  color: var(--bg-dark);
}

/* Top-Left Hamsa Hand Logo */
.top-left-logo {
  position: absolute;
  top: 16px;
  left: 16px;
  z-index: 4; /* Sits below HUD controls but above background canvas */
  font-size: 3.5rem;
  text-decoration: none;
  cursor: pointer;
  line-height: 1;
  transition: transform 0.15s ease;
  pointer-events: all;
}

.top-left-logo:hover {
  transform: scale(1.15);
}