html,
body {
  margin: 0;
  padding: 0;
}
div#app:empty {
  height: 100dvh;
  width: 100vw;
  color: currentColor;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  position: relative;
}

div#app:empty::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 60px;
  height: 60px;
  border-radius: 50%;
  margin-left: -30px;
  margin-top: -30px;
  border: 5px solid;
  border-color: currentColor;
  border-right-color: transparent;
  animation: spin 1s infinite linear;
}

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

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