They are those hardwood frames, and after ten years or so they are a very orangey warm shade. (Not as bad as the horrific orange pine skirting boards though.)
I'm nervous about painting them, because once they're painted that's it, but my taste is decor is rather cool Scandi hues and I think they jar.
I was reading about a Dutch trend to paint all the window frames in the house the same dark colour, and love the idea as I love Crittal windows, but I'm SCARED.