body {
    opacity: 1;
    -webkit-transition: opacity 0.5s ease-out 0s;
    -moz-transition: opacity 0.5s ease-out 0s;
    -o-transition: opacity 0.5s ease-out 0s;
    transition: opacity 0.5s ease-out 0s;
}

body.fadeout {
    opacity: 0.01;
    transition: none;
}