<div id="loader" class="row mb-2 justify-content-center align-items-center">
  <div class="spinner-grow text-primary"></div>&nbsp;&nbsp;&nbsp;
  <div class="spinner-grow text-danger"></div>&nbsp;&nbsp;&nbsp;
  <div class="spinner-grow text-warning"></div>&nbsp;&nbsp;&nbsp;
  <div class="spinner-grow text-success"></div>
</div>