form.checkout.hide-submit-button button[type=submit] {
  opacity: 0;
  pointer-events: none;
  position: absolute;
}

div.woocommerce div.thwmsc-buttons #action-submit {
  display: none;
}
div.woocommerce div.thwmsc-buttons #action-submit.active {
  display: inline-block;
}