html, body {
  background: #353536;
  height: 100%;
  margin: 0;
}
.content{
  display: flex;
  align-content: center;
  justify-content: center;
  align-items: center;
  height: 100%;
}
.content .logo{
  width: 350px;
  animation: fadeIn 3s;
}

@keyframes fadeIn {
  0% { opacity: 0; }
  100% { opacity: 1; }
}