[UserPage] Make UserPage theme agnostic

[G-Ambatte]

Your idea:

As Homebrewery introduces more themes than just straight 5E PHB, having other parts of the website - like the UserPage - use the 5E PHB style becomes inappropriate. I suggest - once Themes are live - we alter the UserPage style to a theme-agnostic style, possibly mimicking the new UI Page style.

Please confirm:

• [X] I have searched the Issues tracker for any duplicate requests and found none.

[dbolack-ab]

Are you thinking of pushing it down to Blank or a distinct new theme?