.neon {
  color: #fff;
  text-shadow:
    0 0 5px #fff,
    0 0 10px #ff00ff,
    0 0 20px #ff00ff,
    0 0 40px #ff00ff,
    0 0 80px #ff00ff;
  animation: flicker 2s infinite alternate;
}
@keyframes flicker {
  0%, 19%, 21%, 23%, 25%, 54%, 56%, 100% { opacity: 1; }
  20%, 24%, 55% { opacity: 0.4; }
}
.transition-height {
  transition: max-height 0.4s ease;
}