<button class="radikalwp-btn-flip"><span class="radikalwp-btn-flip-f">ارسال پیام<//span><span class="radikalwp-btn-flip-b">در خدمتیم ✉<//span><//button>

.radikalwp-btn-flip {
  position: relative;
  padding: 0;
  width: 150px;
  height: 48px;
  font-family: inherit;
  border: none;
  background: transparent;
  cursor: pointer;
  perspective: 600px;
}
.radikalwp-btn-flip-f,
.radikalwp-btn-flip-b {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14.5px;
  font-weight: 700;
  border-radius: 12px;
  backface-visibility: hidden;
  transition: transform .5s cubic-bezier(.4, .2, .2, 1);
}
.radikalwp-btn-flip-f { color: #fff; background: #4f46e5; }
.radikalwp-btn-flip-b { color: #4f46e5; background: #e0e7ff; transform: rotateX(180deg); }
.radikalwp-btn-flip:hover .radikalwp-btn-flip-f { transform: rotateX(180deg); }
.radikalwp-btn-flip:hover .radikalwp-btn-flip-b { transform: rotateX(0); }