With custom Limesurvey admin themes you can change the look and feel of the Limesurvey admin interface. This does not affect the content or menu items shown to survey adminsitrators. For this there is a feature to change the the admin back-end menus. You can also define each menu item for every menu section. Furthermore, there is a Limesurvey feature to adjust the blocks/icons listed at the main admin screen. That screen is presented every time you log in to Limesurvey.
A custom Limesurvey admin theme also supports adding your own logo and favicon to Limesurvey. With some further adjustments (we can help with that) it is even possible to add your own links or footer.