body, div {
    margin:0;
    justify-content: center;
    display: flex;
    align-items: center;
    animation-name:mega;
    animation-duration: 150ms;
    animation-iteration-count: infinite;
    animation-direction: alternate;
}
a {
    margin:0;
    justify-content: center;
    display: flex;
    align-items: center;
    animation-name:mega2;
    animation-duration: 50ms;
    animation-iteration-count: infinite;
    animation-direction: alternate; 
}
body > div {
    width: 100vw;
    height:100vh;
    animation-delay: 0ms;
}
body > div > div {
    width: 80%;
    height:80%;
    animation-delay: 50ms;
}
body > div > div > div {
    width: 80%;
    height:80%;
    animation-delay: 100ms;
}
body > div > div > div > div {
    width: 80%;
    height:80%;
    animation-delay: 150ms;
}
body > div > div > div > div > div {
    width: 80%;
    height:80%;
    animation-delay: 200ms;
}
body > div > div > div > div > div > div {
    width: 80%;
    height:80%;
    animation-delay: 250ms;
}
body > div > div > div > div > div > div > div {
    width: 80%;
    height:80%;
    animation-delay: 300ms;
}
body > div > div > div > div > div > div > div > div {
    width: 80%;
    height:80%;
    animation-delay: 350ms;

}

@keyframes mega {
    0%{background-color: black;}
    100%{background-color: white;}
}
@keyframes mega2 {
    0%{color: black;}
    100%{color: white;}
}