body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
}

#logo {
  opacity: 0;
  transition: opacity 1s ease-in-out;
  max-width: 100%;
  max-height: 100%;
}

#logo.fade-in {
  opacity: 1;
}