See also Where to put custom CSS file.. | NodeBB.
Another possibility is a custom css file overriding the others by having the last <link rel="stylesheet" href="..." /> line in the theme source.
I've got a question regarding customizing the content of emails as the ones users receive when they got banned, invited and so on.
I'm aware of the fact that I can see and edit the source code of them, but ...
Where do I find the templates as for [[email:banned.text3]]?
Where can i find and edit the underlying text?
Those are language tags, and their source strings can be found in public/languages
Thank you @julian !
Just for reassurance - I can request some changes for reasons like e.g. translation mistakes but I can't customize the text completely so that it would be very specific to my community, right?
All of our translation efforts are handled on Transifex (https://www.transifex.com/nodebb/nodebb/), but in general, yes... fixes and incorrect translations would be handled there, and custom changes specific to your community you'd make to those files directly.