enso/app/gui/view/documentation/assets/spinner.html

<div>
  <style>
    .spinner {
      margin: 40vh auto;
      width: 70px;
      text-align: center;
    }

    .spinner > div {
      width: 18px;
      height: 18px;
      background-color: rgb(50, 48, 47);

      border-radius: 100%;
      display: inline-block;
      animation: sk-bouncedelay 1.4s infinite ease-in-out both;
    }

    .spinner .bounce1 {
      animation-delay: -0.32s;
    }

    .spinner .bounce2 {
      animation-delay: -0.16s;
    }

    @keyframes sk-bouncedelay {
      0%,
      80%,
      100% {
        transform: scale(0);
      }
      40% {
        transform: scale(1);
      }
    }
  </style>
  <div class="spinner">
    <div class="bounce1"></div>
    <div class="bounce2"></div>
    <div class="bounce3"></div>
  </div>
</div>