show more button

You can adjust it using custom css styles:

.gallery-ID .ftg-filters a {
    background-color: #fc4000 !important;
    color: #e9ecef !important;
    border-color: #000 !important;
}

.gallery-ID .ftg-filters a:hover,
.gallery-ID .ftg-filters a.selected,
.gallery-ID .ftg-filters a.selected {
    background-color: #fccfaa !important;
    color: #0000 !important;
    border-color: #fc4000 !important;
}

Note: Change the ID with your grid identifier. You can find it in the short code. E.g. [gridkit id=23], then the css selector should be .gallery-23