<button class="radikalwp-btn-underline">مطالعه راهنما<//button>

.radikalwp-btn-underline {
  position: relative;
  padding: 6px 2px;
  font-family: inherit;
  font-size: 16px;
  font-weight: 600;
  color: #334155;
  background: transparent;
  border: none;
  cursor: pointer;
}
.radikalwp-btn-underline::after {
  content: '';
  position: absolute;
  bottom: 0;
  right: 0;
  width: 100%;
  height: 2px;
  background: #6366f1;
  transform: scaleX(0);
  transform-origin: right;
  transition: transform .3s ease;
}
.radikalwp-btn-underline:hover { color: #6366f1; }
.radikalwp-btn-underline:hover::after { transform: scaleX(1); }