/* (A) USE ::BEFORE TO CREATE A LOADING SPINNER */
.dropload::before {
  content: "";
  background-image: url("/static/images/loading.gif");
  background-repeat: no-repeat;
  background-position: center;
}

/* (B) DIMENSIONS */
.dropload { max-width: 320px; } /* optional */
.dropload select, .dropload::before {
  width: 100%;
  height: 40px;
}

/* (C) POSITION LOADING SPINNER OVER DROPDOWN */
.dropload { position: relative; }
.dropload select { z-index: 1; }
.dropload::before {
  position: absolute;
  top: 0; left: 0;
  z-index: 2;
}

/* (D) "DISABLED BY DEFAULT" */
.dropload select {
  pointer-events: none;
  opacity: 0.5;
}

/* (E) HIDE SPINNER WHEN DONE LOADING */
.done.dropload select {
  pointer-events: auto;
  opacity: 1;
}
.done.dropload::before { display: none; }