Styling customisation

Normally, customising TinyMCE's appearance means creating a new theme, compiled in LESS. For most cases that works (and is the recommended option, because it allows TinyMCE to support it), but for Deserted Chateau it isn't enough.

The problem - LESS requires us to have known values for each variable at compile time, and this conflicts with Deserted Chateau's theme functionality. Therefore we directly override various CSS values instead, and inject CSS stylesheets into the editor's iFrame to override the default styling as needed.