Fix FoUC. Show the 'hidden' elements at next tick.

fix-fouc.md

Put these code in your app.

<style>
.fix-fouc {
  opacity: 0;
  /* use this one if you need more compatibility */
  /* display: none;  */
}
</style>

<script>
$(function() {
  setTimeout(function() {
    $('.fix-fouc').removeClass('fix-fouc');
  },0);
);
</script>

Then add class fix-fouc on flashing elements.