<button class="radikalwp-btn-brutal">دانلود رایگان<//button>

.radikalwp-btn-brutal {
  padding: 12px 30px;
  font-family: inherit;
  font-size: 15px;
  font-weight: 900;
  color: #111111;
  background: #facc15;
  border: 3px solid #111111;
  border-radius: 6px;
  cursor: pointer;
  box-shadow: 7px 7px 0 #111111;
  transition: transform .15s ease, box-shadow .15s ease;
}
.radikalwp-btn-brutal:hover {
  transform: translate(-3px, -3px);
  box-shadow: 10px 10px 0 #111111;
}
.radikalwp-btn-brutal:active {
  transform: translate(2px, 2px);
  box-shadow: 3px 3px 0 #111111;
}