.snow-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 9999;
  opacity: 0;
  transition: opacity 0.8s ease;
}

.snow-canvas.active {
  opacity: 1;
}

/* Atmosphere glow overlay — warm firelight radial */
.atm-glow-layer {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  background: transparent;
  transition: background 3s ease;
}

/* Cherenkov reactor pulse overlay */
.cherenkov-pulse-layer {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  opacity: 0;
  background: radial-gradient(
    ellipse at 50% 70%,
    rgba(58, 143, 212, 0.10) 0%,
    rgba(30, 80, 160, 0.04) 40%,
    transparent 70%
  );
  transition: opacity 2s ease;
}

.cherenkov-pulse-layer.active {
  animation: cherenkov-bg-pulse 4s ease-in-out infinite;
}

@keyframes cherenkov-bg-pulse {
  0%, 100% { opacity: 0.4; }
  50%      { opacity: 1; }
}