button {
  --purple: #9B7EDA;
  font-size: 18px;
  padding: 0.8em 3em;
  letter-spacing: 0.08em;
  position: relative;
  font-family: inherit;
  border-radius: 0.6em;
  overflow: hidden;
  transition: all 0.3s;
  line-height: 1.4em;
  border: 2px solid var(--purple);
  background: linear-gradient(to right, rgba(155, 126, 218, 0.1) 1%, transparent 40%, transparent 60%, rgba(155, 126, 218, 0.1) 100%);
  color: var(--purple);
  box-shadow: inset 0 0 10px rgba(155, 126, 218, 0.4), 0 0 9px 3px rgba(155, 126, 218, 0.1);
}

button:hover {
  color: #BFA3F3;
  box-shadow: inset 0 0 10px rgba(155, 126, 218, 0.6), 0 0 9px 3px rgba(155, 126, 218, 0.2);
}

button:before {
  content: "";
  position: absolute;
  left: -4em;
  width: 4em;
  height: 100%;
  top: 0;
  transition: transform .4s ease-in-out;
  background: linear-gradient(to right, transparent 1%, rgba(155, 126, 218, 0.1) 40%, rgba(155, 126, 218, 0.1) 60%, transparent 100%);
}

button:hover:before {
  transform: translateX(15em);
}