.scald-menu .add-buttons .import-museum-icon {
    background: url(../icons/museum.png) 50% 50% no-repeat;
    background-size: 30px 30px;
}

.scald-menu .add-buttons .import-museum-icon:hover {
    background: url(../icons/museum-color.png) 50% 50% no-repeat;
    background-size: 30px 30px;
}