/**
 * Project: Meta Quest 3 Mixed Reality Ball Physics Sandbox
 * Version: 2026.10.08.15.04.00
 * Purpose: Vanilla CSS styles, design tokens, glassmorphism overlays, and responsive layout.
 */

:root {
  /* Color Tokens */
  --bg-dark: #0a0e17;
  --bg-card: rgba(18, 25, 38, 0.75);
  --border-card: rgba(255, 255, 255, 0.12);
  --accent-cyan: #00f0ff;
  --accent-blue: #0084ff;
  --accent-glow: rgba(0, 240, 255, 0.4);
  --text-main: #f0f4fc;
  --text-muted: #8b9bb4;
  --success-color: #00ffaa;
  --warning-color: #ffaa00;

  /* Typography */
  --font-family-display: 'Outfit', -apple-system, sans-serif;
  --font-family-mono: 'JetBrains Mono', monospace;

  /* Layout & Spacing */
  --max-content-width: 640px;
  --radius-lg: 20px;
  --radius-md: 12px;
  --radius-full: 9999px;
  --transition-smooth: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body, html {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background-color: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--font-family-display);
  -webkit-font-smoothing: antialiased;
}

#app {
  position: relative;
  width: 100vw;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Background canvas renders Three.js fallback or passthrough */
canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
}

/* Overlay UI for entering WebXR session */
#overlay {
  position: relative;
  z-index: 10;
  width: 90%;
  max-width: var(--max-content-width);
  padding: 2.5rem 2rem;
  background: var(--bg-card);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.6), 0 0 30px rgba(0, 240, 255, 0.1);
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
  text-align: center;
  transition: opacity var(--transition-smooth), transform var(--transition-smooth);
}

body.in-xr #overlay {
  display: none !important;
}

.header {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.35rem 0.85rem;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-cyan);
  background: rgba(0, 240, 255, 0.1);
  border: 1px solid rgba(0, 240, 255, 0.3);
  border-radius: var(--radius-full);
}

h1 {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, #ffffff 40%, var(--accent-cyan) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.subtitle {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.5;
  max-width: 480px;
}

.action-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.primary-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  width: 100%;
  max-width: 380px;
  padding: 1.1rem 1.75rem;
  font-family: var(--font-family-display);
  font-size: 1.05rem;
  font-weight: 700;
  color: #050b14;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  box-shadow: 0 8px 24px var(--accent-glow);
  transition: all var(--transition-smooth);
}

.primary-btn:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(0, 240, 255, 0.6);
}

.primary-btn:active:not(:disabled) {
  transform: translateY(0);
}

.primary-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  box-shadow: none;
}

.btn-icon {
  font-size: 1.3rem;
}

.status-indicator {
  font-family: var(--font-family-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.85rem;
  text-align: left;
}

.feature-item {
  padding: 0.85rem 1rem;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-md);
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.feature-icon {
  font-size: 1.25rem;
  margin-bottom: 0.2rem;
}

.feature-item strong {
  font-size: 0.85rem;
  color: var(--text-main);
}

.feature-item span {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.footer {
  font-size: 0.75rem;
  color: var(--text-muted);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding-top: 1rem;
}

@media (max-width: 520px) {
  .features-grid {
    grid-template-columns: 1fr;
  }
  h1 {
    font-size: 1.75rem;
  }
}