.t4b_filter_image {
    opacity: 0.2;
    filter: grayscale(100%);
    transition: all 0.4s;
}

.t4b_filter_image:hover {
    opacity: 1;
    filter: grayscale(0);
    transition: all 0.4s;
}

.t4b_filter_image_hover {
    opacity: 1;
    filter: grayscale(0);
    transition: all 0.4s;
}

.t4b_filter_image_hover_out {
    opacity: 0.2;
    filter: grayscale(100%);
    transition: all 0.4s;
}