loading-indicator.html

<style>
  body,
  html,
  #<%= globals.id %> {
    background: <%= options.background %>;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 0;
    padding: 0;
  }

  .loading-indicator {
    width: 60px;
    height: 60px;
    position: relative;

    -webkit-animation: rotate 6s infinite ease;
    animation: rotate 6s infinite ease;
  }
  .loading-indicator .logo {
    background-color: white;
    border-radius: 8px;
    width: 100%;
    height: 100%;
    position: absolute;
  }

  .loading-indicator .logo::before {
    content: '';
    position: absolute;
    top: -10px;
    left: -10px;
    background-image: url('/icon-small.png');
    background-size: contain;
    width: 80px;
    height: 80px;
  }

  @-webkit-keyframes rotate {
    100% {
      -webkit-transform: rotate(360deg);
    }
  }
  @keyframes rotate {
    100% {
      transform: rotate(360deg);
      -webkit-transform: rotate(360deg);
    }
  }
</style>

<div class="loading-indicator">
  <div class="logo"></div>
</div>