body article * {
    -webkit-animation: fadein 0.5s; /* Safari and Chrome */
       -moz-animation: fadein 0.5s; /* Firefox */
        -ms-animation: fadein 0.5s; /* Internet Explorer */
         -o-animation: fadein 0.5s; /* Opera */
            animation: fadein 0.5s;
}

@keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Firefox */
@-moz-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Safari and Chrome */
@-webkit-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/* Internet Explorer */
@-ms-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}​

/* Opera */
@-o-keyframes fadein {
    from { opacity: 0; }
    to   { opacity: 1; }
}​