I seek a proper term for a subject area of and/or targeting of specific audience and/or interests by a website .

For ex., a website can be devoted to fishing, English grammar, programming, etc.
Such terms as "theme", "style" are overloaded and commonly understood in programming and website design as overall gamma of colors (grapical look and feel) applied to all graphic elements over all webpages of a site.

What would be a more proper (specific), less ambiguousand clear without additional explanations term?
I understood that I formulated my question incorrectly.

Well, I am proofreading texts that describe a game-like plugin (interactive puzzles) for websites.
It may have different scenes, actors (graphic elements) , scenarios and types.

And, I need to refer to the possibility of customization of this plugin to match the look and feel of a website it is going to be incorporated into.

I need to refer to subject (interest, audience, interests targeted by) a website (and the site can be any) respectively being matched (customized) in this plugin.

Currently used terms for this are "theme" (subject of a website and of a game) and "thematic plugin" for a service proposing customization of this product to match a website's feel for which I would like to find other more appropriate terms or synonyms.