.neon-button {
  display: inline-block;
  padding: 12px 32px;
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: #00ffff;
  background: transparent;
  border: 2px solid #00ffff;
  border-radius: 8px;
  cursor: pointer;
  text-shadow: 0 0 5px #00ffff;
  box-shadow: 0 0 10px #00ffff,
    0 0 20px #00ffff66,
    0 0 40px #00ffff33,
    inset 0 0 10px #00ffff33;
  animation: neon-pulse 2s ease-in-out infinite;
  transition: all 0.3s ease;
}

.neon-button:hover {
  color: #000;
  background: rgba(0, 255, 255, 0.2);
  box-shadow: 0 0 15px #00ffff,
    0 0 30px #00ffff88,
    0 0 60px #00ffff44,
    inset 0 0 15px #00ffff44;
  text-shadow: 0 0 10px #00ffff;
}

@keyframes neon-pulse {
  0%, 100% {
    box-shadow: 0 0 10px #00ffff,
    0 0 20px #00ffff66,
    0 0 40px #00ffff33,
    inset 0 0 10px #00ffff33;
  }
  50% {
    box-shadow: 0 0 20px #00ffff,
      0 0 40px #00ffff88,
      0 0 80px #00ffff44,
      inset 0 0 20px #00ffff44;
  }
}

<button class="neon-button">Click Me</button>