<button class="radikalwp-btn-neon">بازی کن<//button>

.radikalwp-btn-neon {
  padding: 13px 34px;
  font-family: inherit;
  font-size: 15px;
  font-weight: 700;
  color: #e9d5ff;
  background: #17103a;
  border: 1.5px solid #a855f7;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: 0 0 12px rgba(168, 85, 247, .35), inset 0 0 12px rgba(168, 85, 247, .12);
  transition: box-shadow .25s ease, color .25s ease, transform .2s ease;
}
.radikalwp-btn-neon:hover {
  color: #fff;
  box-shadow: 0 0 26px rgba(168, 85, 247, .75), inset 0 0 18px rgba(168, 85, 247, .3);
  transform: translateY(-1px);
}