#shiny-shadow {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
  background: #1e2124;
}

button {
  border: 2px;
  background: transparent;
  text-transform: uppercase;
  outline: none;
  overflow: hidden;
  position: relative;
}

span {
  z-index: 20;
}

button:after {
  content: '';
    display: block;
    position: absolute;
    top: -350px;
    left: -320px;
    background: white;
    width: 100px;
    height: 2000px;
    opacity: 20%;
    transform: rotate(-45deg);
}

button:hover:after {
  left: 200%;
  transition: all 600ms cubic-bezier(0.3, 1, 0.2, 1);
   -webkit-transition: all 600ms cubic-bezier(0.3, 1, 0.2, 1);
}