:root {
  /* Dark Mode Tokens (Default Cyber-Glass Aesthetic) */
  --bg: #05070d;
  --bg-radial: radial-gradient(circle at top, #12233d 0%, #08111d 45%, #05070d 100%);
  --surface: #111827;
  --card: #1b2234;
  --primary: #00d9ff;
  --primary-glow: #00d9ff;
  --secondary: #4f7cff;
  --secondary-glow: #4f7cff;
  --accent: #ff0077;
  --accent-glow: #ff0077;
  --success: #00ff88;
  --warning: #ffb700;
  --text: #ffffff;
  --text-secondary: #b6c2d9;
  --text-muted: #64748b;
  
  --glass-bg: rgba(27, 34, 52, 0.65);
  --glass-border: rgba(0, 217, 255, 0.2);
  --glass-border-hover: rgba(0, 217, 255, 0.6);
  --shadow-glow: 0 0 25px rgba(0, 217, 255, 0.3);
  
  --font-main: 'Plus Jakarta Sans', sans-serif;
  --font-display: 'Inter', sans-serif;

  --bg-dark: var(--bg);
  --bg-card: var(--card);
  --text-main: var(--text);
}

body.light {
  /* Light Mode Tokens */
  --bg: #edf3ff;
  --bg-radial: radial-gradient(circle at top, #e0ebff 0%, #edf3ff 50%, #f4f8ff 100%);
  --surface: #ffffff;
  --card: #f8fbff;
  --primary: #0078ff;
  --primary-glow: #0078ff;
  --secondary: #3b82f6;
  --secondary-glow: #3b82f6;
  --accent: #e11d48;
  --text: #111827;
  --text-secondary: #475569;
  --text-muted: #64748b;
  
  --glass-bg: rgba(255, 255, 255, 0.85);
  --glass-border: rgba(0, 120, 255, 0.2);
  --glass-border-hover: rgba(0, 120, 255, 0.5);
  --shadow-glow: 0 0 20px rgba(0, 120, 255, 0.2);

  --bg-dark: var(--bg);
  --bg-card: var(--card);
  --text-main: var(--text);
}

html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  min-height: 100vh;
  overflow-x: hidden;

  background:
    radial-gradient(circle at top left, rgba(0, 217, 255, 0.15), transparent 35%),
    radial-gradient(circle at bottom right, rgba(59, 130, 246, 0.12), transparent 35%),
    linear-gradient(180deg, #0b1324 0%, #08111d 40%, #05070d 100%) !important;

  color: #ffffff !important;
  font-family: 'Plus Jakarta Sans', sans-serif;
  line-height: 1.5;
  user-select: none;
  -webkit-user-select: none;
  display: flex;
  flex-direction: column;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: -2;

  background:
    radial-gradient(circle at 15% 20%, rgba(0, 217, 255, 0.18), transparent 30%),
    radial-gradient(circle at 80% 80%, rgba(59, 130, 246, 0.12), transparent 35%);

  animation: bgFloat 18s ease-in-out infinite;
}

@keyframes bgFloat {
  0% { transform: translate(0, 0); }
  50% { transform: translate(40px, -25px); }
  100% { transform: translate(0, 0); }
}

body[data-theme="light"] {
  background: #eef4ff !important;
  color: #111827 !important;
}

body[data-theme="light"]::before {
  display: none;
}

/* --------------------------------------------------------------------------
   GLASSMORPHISM TOP BAR HEADER
   -------------------------------------------------------------------------- */
.shell-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
  background: rgba(18, 20, 36, 0.75);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--glass-border);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
  z-index: 100;
  flex-wrap: wrap;
  gap: 1rem;
}

.shell-title-group {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.shell-title {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 700;
  background: linear-gradient(135deg, #ffffff, var(--primary-glow));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.01em;
}

.shell-scores {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.shell-score-box {
  background: rgba(0, 240, 255, 0.08);
  border: 1px solid rgba(0, 240, 255, 0.2);
  padding: 0.35rem 0.9rem;
  border-radius: 10px;
  text-align: center;
  min-width: 80px;
}

.shell-score-label {
  font-size: 0.65rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.shell-score-val {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary-glow);
}

.shell-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Control Buttons */
.shell-btn {
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  color: var(--text-main);
  width: 38px;
  height: 38px;
  border-radius: 10px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s ease;
  outline: none;
}

.shell-btn:hover {
  background: rgba(0, 240, 255, 0.15);
  border-color: var(--primary-glow);
  color: var(--primary-glow);
  transform: translateY(-2px);
  box-shadow: 0 0 12px rgba(0, 240, 255, 0.3);
}

.shell-btn svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

/* --------------------------------------------------------------------------
   MAIN STAGE CONTAINER
   -------------------------------------------------------------------------- */
.shell-stage {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  position: relative;
}

/* Loading Screen Overlay */
.shell-loader {
  position: fixed;
  inset: 0;
  background: #080911;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  transition: opacity 0.4s ease, visibility 0.4s ease;
}

.shell-loader.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.spinner {
  width: 50px;
  height: 50px;
  border: 3px solid rgba(0, 240, 255, 0.15);
  border-top-color: var(--primary-glow);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.shell-loader-text {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--primary-glow);
  text-transform: uppercase;
}

/* Pause & Game Over Overlays */
.shell-overlay {
  position: absolute;
  inset: 0;
  background: rgba(8, 9, 17, 0.88);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 500;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  border-radius: 16px;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}

.shell-overlay.active {
  opacity: 1;
  visibility: visible;
}

.shell-overlay-title {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 800;
  color: var(--primary-glow);
  text-transform: uppercase;
}

/* Primary Action Buttons */
.btn-action {
  padding: 0.75rem 1.8rem;
  font-family: var(--font-main);
  font-size: 0.95rem;
  font-weight: 700;
  border-radius: 50px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.25s ease;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
}

.btn-action-primary {
  background: linear-gradient(135deg, var(--primary-glow), var(--secondary-glow));
  color: #ffffff;
  box-shadow: 0 4px 20px rgba(0, 240, 255, 0.4);
}

.btn-action-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 25px rgba(0, 240, 255, 0.6);
}

.btn-action-secondary {
  background: var(--glass-bg);
  border-color: var(--glass-border);
  color: var(--text-main);
}

.btn-action-secondary:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: var(--primary-glow);
}