Nuxt/lib/app/views/loading/rectangle-bounce.html

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

.spinner {
  margin: 100px auto;
  width: 50px;
  height: 40px;
  text-align: center;
  font-size: 10px;
}

.spinner > div {
  background-color: <%= options.color %>;
  height: 100%;
  width: 6px;
  display: inline-block;

  -webkit-animation: sk-stretchdelay 1.2s infinite ease-in-out;
  animation: sk-stretchdelay 1.2s infinite ease-in-out;
}

.spinner .rect2 {
  -webkit-animation-delay: -1.1s;
  animation-delay: -1.1s;
}

.spinner .rect3 {
  -webkit-animation-delay: -1.0s;
  animation-delay: -1.0s;
}

.spinner .rect4 {
  -webkit-animation-delay: -0.9s;
  animation-delay: -0.9s;
}

.spinner .rect5 {
  -webkit-animation-delay: -0.8s;
  animation-delay: -0.8s;
}

@-webkit-keyframes sk-stretchdelay {
  0%, 40%, 100% { -webkit-transform: scaleY(0.4) }
  20% { -webkit-transform: scaleY(1.0) }
}

@keyframes sk-stretchdelay {
  0%, 40%, 100% {
    transform: scaleY(0.4);
    -webkit-transform: scaleY(0.4);
  }  20% {
    transform: scaleY(1.0);
    -webkit-transform: scaleY(1.0);
  }
}
</style>

<div class="spinner">
  <div class="rect1"></div>
  <div class="rect2"></div>
  <div class="rect3"></div>
  <div class="rect4"></div>
  <div class="rect5"></div>
</div>

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