.btn-retour {
  display: inline-block;
  padding: 12px 24px;
  background: #fafafa;
  color: #2f2f2f;
  border: 1px solid #ccc;
  border-radius: 5px;
  font-family: "Cormorant Garamond", serif;
  font-size: 18px;
  text-decoration: none;
  position: relative;
  overflow: hidden;
}
.btn-retour::after {
  content: "";
  position: absolute;
  top: 0; left: -100%;
  width: 100%; height: 100%;
  background: rgba(217, 251, 214, 0.6);
  transition: left 0.4s ease;
}
.btn-retour:hover::after {
  left: 0;
}