Elemtentor Animated Border

selector.fadeIn::before {
    content: '';
    width: 100%;
    height: 100%;
    position: absolute;
    z-index: -3;
    background-repeat: no-repeat;
    background-image: -webkit-gradient(linear, left top, right top, color-stop(100%, #C9C9C9), to(#C9C9C9)), -webkit-gradient(linear, left top, left bottom, color-stop(100%, #C9C9C9), to(#C9C9C9)), -webkit-gradient(linear, left top, right top, color-stop(100%, #C9C9C9), to(#C9C9C9)), -webkit-gradient(linear, left top, left bottom, color-stop(100%, #C9C9C9), to(#C9C9C9));
    background-image: -o-linear-gradient(left, #C9C9C9 100%, #C9C9C9 100%), -o-linear-gradient(top, #C9C9C9 100%, #C9C9C9 100%), -o-linear-gradient(left, #C9C9C9 100%, #C9C9C9 100%), -o-linear-gradient(top, #C9C9C9 100%, #C9C9C9 100%);
    background-image: linear-gradient(to right, #C9C9C9 100%, #C9C9C9 100%), linear-gradient(to bottom, #C9C9C9 100%, #C9C9C9 100%), linear-gradient(to right, #C9C9C9 100%, #C9C9C9 100%), linear-gradient(to bottom, #C9C9C9 100%, #C9C9C9 100%);
    background-size: 0 3px, 3px 0, 0 3px, 3px 0;
    background-position: 0 0, 100% 0, 100% 100%, 0 100%;
    -webkit-animation: bordere 2.3s cubic-bezier(0.19, 1, 0.22, 1) forwards 1.3s;
    animation: bordere 2.3s cubic-bezier(0.19, 1, 0.22, 1) forwards 1.3s;
}

@-webkit-keyframes bordere {
    0% {
        background-size: 0 3px, 3px 0, 0 3px, 3px 0;
    }
    25% {
        background-size: 100% 3px, 3px 0, 0 3px, 3px 0;
    }
    50% {
        background-size: 100% 3px, 3px 100%, 0 3px, 3px 0;
    }
    75% {
        background-size: 100% 3px, 3px 100%, 100% 3px, 3px 0;
    }
    100% {
        background-size: 100% 3px, 3px 100%, 100% 3px, 3px 100%;
    }
}

@keyframes bordere {
    0% {
        background-size: 0 3px, 3px 0, 0 3px, 3px 0;
    }
    25% {
        background-size: 100% 3px, 3px 0, 0 3px, 3px 0;
    }
    50% {
        background-size: 100% 3px, 3px 100%, 0 3px, 3px 0;
    }
    75% {
        background-size: 100% 3px, 3px 100%, 100% 3px, 3px 0;
    }
    100% {
        background-size: 100% 3px, 3px 100%, 100% 3px, 3px 100%;
    }
}