button {
  padding: 0.9em 1.8em;
  text-transform: uppercase;
  text-decoration: none;
  letter-spacing: 4px;
  color: transparent;
  border: 3px solid #ff0;
  font-size: 14px;
  position: relative;
  font-family: inherit;
  background: transparent;
  cursor: pointer;
}

button::before {
  content: "button";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: #363636;
  color: #ff0;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: all 0.5s;
}

button:hover::before {
  left: 100%;
  transform: scale(0) rotateY(360deg);
  opacity: 0;
}

button::after {
  content: "button";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background-color: #363636;
  color: #ff0;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: all 0.5s;
  transform: scale(0) rotateY(0deg);
  opacity: 0;
}

button:hover::after {
  left: 0;
  transform: scale(1) rotateY(360deg);
  opacity: 1;
}