How to make a smooth transition animation to another page?

Question

css

How to use CSS3 to make a click on a link a smooth transition (FadeIn / FadeOut) to another page.

Answer 1

smoothstate.com/index.html

Answer 2

@keyframes fade{

    from {
      opacity: 0;
    }

    to{
      opacity: 1;
    }
}

body {
  animate: fade 1s;
}