[feature request] Add CSS to the internal web pages

[Freyj]

To allow for less ugliness

[Freyj]

Need to decide on a color palette and some sort of style at some point

[Freyj]

http://colormind.io/ to find not too ugly colours and replace the current random ones

[Freyj]

Trying to have different css styles for pages of different games (like respect the classic traveller feel on the CT pages, and have a DnD feel on the DnD ones)