.shadow1:hover {
    position:relative;
    background:linear-gradient(0deg,rgb(255, 255, 255),#e9e5e5);
}
.shadow1:hover:before,
.shadow1:hover:after {
    content:'';
    position:absolute;
    top:-2px;
    left:-2px;
    background:linear-gradient(45deg,#4d1535,#09093f,#0a270a,#535316,#ff0000,#fb0094,#09093f
    ,#116411,#ffff00,#5c1212);
    background-size:400%;
    width:calc(100% + 4px);
    height:calc(100% + 4px);
    z-index:-1;
    animation:animate 20s linear infinite;


}

.shadow1:hover:after {
    filter:blur(20px);

}

@keyframes animate {
    0% {
        background-position:0 0;
    }
    50% {
        background-position:300% 0;
    }
    100% {
        background-position:0 0;
    }
}