.ephemeral {
    -webkit-animation: cssAnimation 5s forwards; 
    animation: cssAnimation 5s forwards;
}

@keyframes cssAnimation {
    0%   {opacity: 1;}
    90%  {opacity: 1;}
    100% {opacity: 0;}
}
@-webkit-keyframes cssAnimation {
    0%   {opacity: 1;}
    90%  {opacity: 1;}
    100% {opacity: 0;}
}