#bg {position:fixed; width:100vw; height:100vh; top:0; left:0; padding:0; z-index:-15;}
.slide {position:absolute; height:100%; width:100%; background-size:cover; background-position:50% 50%;}
.slideActive {animation-name:fade; animation-duration:2.5s; z-index:-13;}
.slideBehind {z-index:-15;}

@keyframes fade {
  0%    {opacity:0}
  20%    {opacity:0}
  100%  {opacity:1}
}

@keyframes rtob {
  0% {background-color:#F10}
  100% {background-color:#000}
}