#adminmenu .toplevel_page_islash .wp-menu-image {
    background-image: url('../../public/images/islash-icon.svg') !important;
    background-size: 16px;
    background-position: center;
    background-repeat: no-repeat;
    border: 0;
}

#adminmenu .toplevel_page_islash .wp-menu-image::before {
    content: "";
}