Personas are free, easy-to-install "skins" for Firefox. Personas Plus extends that built-in functionality to give you even more control and easier access to new, popular, and your own favorite Personas.
Manage your installed personas (lightweight themes).
Change your Personas theme on each browser load.
This one is a Star Trek theme, using the LCARS interface known of Federation Star Ships (heavily used in The Next Generation and Voyager series). It's got lot of rounded borders and hover (mouse-over) effects, be aware that it may look and feel...
Preview lightweight theme when hover on menuitems in Apply Theme menu.