Dynamic Button
Code Snippet

button.product-form__submit:before,
button.product-form__submit:after {
  content: "";
  box-shadow: unset;
  position: absolute;
  left: -2px;
  top: -2px;
  background: #000;
  background-size: 397%;
  width: calc(100% + 4px);
  height: calc(100% + 4px);
  z-index: -1;
  animation: steam 2s linear infinite;
  border-radius: 12px;
}

button.product-form__submit {
  border: solid 1px #000;
  border-radius: 12px;
}

button.product-form__submit:after {
  filter: blur(18px);
}

@keyframes steam {
  0% {
    background-position: 0 0;
    opacity: 0;
  }

  50% {
    background-position: 400% 0;
    opacity: 1;
  }

  100% {
    background-position: 0 0;
    opacity: 0;
  }
}