Actually it works but the duration of the animation is 0 seconds on other browsers, because you did not add a prefix -webkit
to work with chrome and Safari.
So it must be
html{
.....
animation-duration:1s;
-webkit-animation-duration: 1s;
}
or you could combine the animation-duration
and animation-name
in one css property which is animation
so it will be
html{
-webkit-animation: fadeInLeftBig 1s;
animation: fadeInLeftBig 1s;
}