Add some Toolbars to see the entire height of the persona image = 3000px by 200px (I don't think the full width of the Persona image can be seen on anything except a wide screen TV display).

Firefox comes with 3 Toolbars, the Menu bar, the Navigation bar, and the Bookmarks toolbar. It may vary depending on your operating system and whether you have Large or Small toolbar icons selected, but on my system I need to have 10 toolbars showing to see the full height of the Persona I have selected. YMMV

View > Toolbars - Customize
Then hit the Add New Toolbar button, name that new toolbar (I named them Spacer 1 -7), and then add a single Space to each new Toolbar. Repeat until you have 7 more Toolbars.
When you're done - hit the Done button.

when I hit "done" it goes back to original. Same if I hit the "x" tab.

Make sure that you place some content like a Space item on each toolbar that you create before closing the Customize window. Empty toolbars are removed automatically.

Another way to do this:

You can create one toolbar (name: PersonaFiller) via "View > Toolbars > Customize" and put a single Space item on it and use code in userChrome.css to set a min-height for that toolbar.

If you do not want to see that toolbar to get more website space then you only need to remove one check-mark via the right-click context menu

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */
#__customToolbar_PersonaFiller {min-height:100px !important;}

Add the code to userChrome.css below the @namespace line.

See:

• http://kb.mozillazine.org/Editing_configuration
• ChromEdit Plus: http://webdesigns.ms11.net/chromeditp.html

Where do I put the code userChrome.ccs? I added spaces, but it was like they all lined up on the same tool bar. Thanks for helping.