.button {
  cursor: pointer;
  position: relative;
  padding: 15px 20px;
  text-decoration: none;
  border: none;
  color: #fff;
  font-size: 1.2em;
  text-transform: uppercase;
  font-family: sans-serif;
  letter-spacing: 4px;
  overflow: hidden;
  background: rgba(255, 255, 255, 0.1);
  box-shadow: 0 5px 5px rgba(0, 0, 0, 0.2);
}
.button:before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 50%;
  height: 100%;
  background: rgba(255, 255, 255, 0.1);
}
.button::after {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.4),
    transparent
  );
  transition: 0.5s;
  transition-delay: 0.5s;
}
.button:hover:after {
  left: 100%;
}
.button span {
  position: absolute;
  display: block;
  transition: 0.5s ease;
}
.button span:nth-child(1) {
  top: 0;
  left: 0;
  width: 0;
  height: 1px;
  background: #fff;
}
.button:hover span:nth-child(1) {
  width: 100%;
  transform: translateX(100%);
}
.button span:nth-child(2) {
  top: 0;
  left: 0;
  width: 1px;
  height: 0;
  background: #fff;
}
.button:hover span:nth-child(2) {
  height: 100%;
  transform: translateY(100%);
}
.button span:nth-child(3) {
  bottom: 0;
  right: 0;
  width: 0;
  height: 1px;
  background: #fff;
}
.button:hover span:nth-child(3) {
  width: 100%;
  transform: translateX(-100%);
}
.button span:nth-child(4) {
  bottom: 0;
  right: 0;
  width: 1px;
  height: 0;
  background: #fff;
}
.button:hover span:nth-child(4) {
  height: 100%;
  transform: translateY(-100%);
}