Single post in Content Appropriateness (Answered!!)

Howdy! Me again worryin about what I can/can't put in me journal. I know that anything pg-15 or 18+ isn't allowed anywhere in the general forums, BUT, at least in terms of fandoms/series/etc: If the series itself is 18+, but the content I post of it is appropriate for the rating of the thread (example: just posting a picture/drawing of a character that is PG, or sharing music from a game, etc) is it alright? Or would that still be considered "18+" and not allowed? Like, not talking about obscure hypotheticals here, if I wanted to share a track from the OST of a rated M game to my PG-13 journal, would that be allowed? :O I mostly just don't know if "no 18+" means like, even mentioning a series that is 18+ isn't allowed or if like, we just can't talk about the 18+ content from that series.