Is your feature request related to a problem? Please describe.
I would like an option to customise CSS/HTML.

Describe the solution you'd like
Some servers would like to customise their BlueMap website to fit their style/theme. There should be a simple way to customise text / certain widgets with the power of HTML and CSS.

Summarizing the discussion from discord for everyone:
You can easily edit/add to the css in the webroot.
If you need to change more of the web-app, cloning the repo and compiling your own version is the way to go :)