#mytxtshadow{
    -webkit-animation: mymove 5s infinite; 
    animation: mymove 5s infinite;
};

@-webkit-keyframes mymove {
    50% {text-shadow: 10px 20px 30px blue;}
};

@keyframes mymove {
    50% {text-shadow: 10px 20px 30px blue;}
};