@keyframes animb {
    0% {filter: sepia(1) opacity(0);}
    25% {filter: sepia(1) opacity(0.25);}
    75% {filter: sepia(0.75) opacity(0.75);}
    100% {filter: sepia(0) opacity(1);}
}

@keyframes animf {
    0% {filter: sepia(0) opacity(1);}
    25% {filter: sepia(0.25) opacity(0.75);}
    75% {filter: sepia(0.75) opacity(0.25);}
    100% {filter: sepia(1) opacity(0);}
}