@keyframes five-s-hide {
    0% { }
    80% { }
    100% { 
        height: 0;
        padding: 0;
        margin: 0;
    }
}

@keyframes five-s-show {
    0% { 
        height: 0;
        padding: 0;
        margin: 0;
    }
    80% { 
        height: 0;
        padding: 0;
        margin: 0;
    }
    100% { }
}

.swap-child > *:nth-child(1) {
    animation: five-s-hide 5s linear 0s 1 normal forwards;
    overflow: hidden;
}
.swap-child > *:nth-child(2) {
    animation: five-s-show 5s linear 0s 1 normal forwards;
    overflow: hidden;
}