@keyframes shine {
    0% {
        background-position-x: -500%;
    }
    100% {
        background-position-x: 500%;
    }
}

#intro {
    background: linear-gradient(95deg, #FFF, #666, #FFF);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: shine 7s alternate-reverse infinite;
    background-size: 85%;
}