loading.html

<style>
body, html, #__nuxt {
  background-color: white;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0;
  padding: 0;
}

.spinner {
  width: 40px;
  height: 40px;
  margin: 100px auto;
  background-color: #dbe1ec;

  border-radius: 100%;
  -webkit-animation: sk-scaleout 1.0s infinite ease-in-out;
  animation: sk-scaleout 1.0s infinite ease-in-out;
}

@-webkit-keyframes sk-scaleout {
  0% { -webkit-transform: scale(0) }
  100% {
    -webkit-transform: scale(1.0);
    opacity: 0;
  }
}

@keyframes sk-scaleout {
  0% {
    -webkit-transform: scale(0);
    transform: scale(0);
  } 100% {
    -webkit-transform: scale(1.0);
    transform: scale(1.0);
    opacity: 0;
  }
}
</style>

<div class="spinner">
  <div class="double-bounce1"></div>
  <div class="double-bounce2"></div>
</div>

<!-- http://tobiasahlin.com/spinkit -->