Creates a CSS-only loading spinner.

loading.css

.is-loading {
  color: transparent !important;
  pointer-events: none;
}

.is-loading:after {
  -webkit-animation: spinAround 500ms infinite linear;
          animation: spinAround 500ms infinite linear;
  border: 2px solid #dbdbdb;
  border-radius: 290486px;
  border-right-color: transparent;
  border-top-color: transparent;
  content: "";
  display: block;
  height: 1em;
  position: relative;
  width: 1em;
  position: absolute;
  left: calc(50% - (1em / 2));
  top: calc(50% - (1em / 2));
  position: absolute !important;
}

@-webkit-keyframes spinAround {
  from {
    -webkit-transform: rotate(0deg);
            transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(359deg);
            transform: rotate(359deg);
  }
}

@keyframes spinAround {
  from {
    -webkit-transform: rotate(0deg);
            transform: rotate(0deg);
  }
  to {
    -webkit-transform: rotate(359deg);
            transform: rotate(359deg);
  }
}

it's a good practice to disable the buttons on click to stop the user from spamming or accidentally pressing the buttons twice while the process is still in progress.

Append to the buttons:

:disabled="loading"