Nuxt/lib/app/views/loading/nuxt.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;
}

.logo {
  animation: turn 2s linear forwards 1s;
  transform: rotateX(180deg);
  position: relative;
  height: 346px;
  width: 536px;
  margin: 50px auto;
}

.triangle {
  position: absolute;
  top: 0;
  left: 0;
  width: 0;
  height: 0;
}
.triangle--one {
  border-left: 210px solid transparent;
  border-right: 210px solid transparent;
  border-bottom: 360px solid #41B883;
}
.triangle--two {
  top: 60px;
  left: 70px;
  animation: goright 0.5s linear forwards 3.5s;
  border-left: 175px solid transparent;
  border-right: 175px solid transparent;
  border-bottom: 300px solid #3B8070;
}
.triangle--three {
  top: 120px;
  left: 70px;
  animation: goright 0.5s linear forwards 3.5s;
  border-left: 140px solid transparent;
  border-right: 140px solid transparent;
  border-bottom: 240px solid #35495E;
}
.triangle--four {
  top: 240px;
  left: 140px;
  animation: godown 0.5s linear forwards 3s;
  border-left: 70px solid transparent;
  border-right: 70px solid transparent;
  border-bottom: 120px solid #fff;
}

@keyframes turn {
  100% {
    transform: rotateX(0deg);
  }
}
@keyframes godown {
  100% {
    top: 360px;
  }
}
@keyframes goright {
  100% {
    left: 140px;
  }
}
</style>

<div class="logo">
<div class="triangle triangle--two"></div>
<div class="triangle triangle--one"></div>
<div class="triangle triangle--three"></div>
<div class="triangle triangle--four"></div>
</div>


<!-- https://codepen.io/alexchopin/pen/jBWrej -->