index.css

body {
  margin: 0px;
  font-family: 'Nunito', sans-serif;
}

canvas {
  position: fixed;
  top: 0;
  left: 0;
}

#app {
  width: 100vw;
  height: 100vh;
  display: flex;
  flex-direction: row;
  justify-content: center;
}

.loader-wrapper {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  background-color: #242f3f;
  display: flex;
  justify-content: center;
  align-items: center;
}

.loader {
  display: inline-block;
  width: 30px;
  height: 30px;
  position: relative;
  border: 4px solid #fff;
  animation: loader 2s infinite ease;
}

.loader-inner {
  vertical-align: top;
  display: inline-block;
  width: 100%;
  background-color: #fff;
  animation: loader-inner 2s infinite ease-in;
}

@keyframes loader {
  0% {
    transform: rotate(0deg);
  }

  25% {
    transform: rotate(180deg);
  }

  50% {
    transform: rotate(180deg);
  }

  75% {
    transform: rotate(360deg);
  }

  100% {
    transform: rotate(360deg);
  }
}

@keyframes loader-inner {
  0% {
    height: 0%;
  }

  25% {
    height: 0%;
  }

  50% {
    height: 100%;
  }

  75% {
    height: 100%;
  }

  100% {
    height: 0%;
  }
}