The universe is the pinnacle of mystery and scale. We can implement a massive, color-shifting, pulsing gas cloud using deep box-shadow spreads and filter: hue-rotate properties.

The Breathing Core

.core {
  width: 100px; height: 100px;
  background: #c026d3;
  border-radius: 50%;
  filter: blur(40px);
  animation: pulseNebula 6s ease-in-out infinite alternate;
}

@keyframes pulseNebula {
  0% { transform: scale(1); filter: blur(40px) hue-rotate(0deg); opacity: 0.7;}
  100% { transform: scale(2.5); filter: blur(80px) hue-rotate(90deg); opacity: 1;}
}

Witness the breathtaking universe breathing dynamically through color and scale in the Live Demo.