<h2 class="radikalwp-txt-neon">NEON<//h2>

.radikalwp-txt-neon {
  margin: 0;
  font-size: 52px;
  font-weight: 900;
  letter-spacing: 6px;
  text-align: center;
  color: #fff;
  text-shadow:
    0 0 6px rgba(236, 72, 153, .9),
    0 0 18px rgba(236, 72, 153, .65),
    0 0 42px rgba(236, 72, 153, .45);
  animation: radikalwp-txt-neon-flicker 4s linear infinite;
}
@keyframes radikalwp-txt-neon-flicker {
  0%, 9%, 11%, 54%, 56%, 100% { opacity: 1; }
  10%  { opacity: .45; }
  55%  { opacity: .6; }
}