Linux puskom-ProLiant-DL385-Gen10 5.4.0-150-generic #167~18.04.1-Ubuntu SMP Wed May 24 00:51:42 UTC 2023 x86_64

/usr/share/themes/Radiance/gtk-3.20/apps/

//usr/share/themes/Radiance/gtk-3.20/apps/gnome-boxes.css

 @define-color bg_menu_row shade (@bg_color, 0.6);

.boxes-menu-row,
.boxes-menu-row:selected {
    color: inherit;
}

button.boxes-menu-row {
  border-radius: 3px;
}

.boxes-menu-row > .dim-label {
    color: shade (@bg_menu_row, 0.6);
}