The style for the website is fixed, and is not able to be tweaked.
The XenForo Standard Style can be used as an alternative.
Edit: link to the details here:
New AFF Website
Are you sure that the website style is fixed? There was discussion some pages back about how the mods etc. chose colours and so on, so there must have been some discussion.
The only thing I can think of is that perhaps not
all of the colours of things were able to be chosen, which may affect e.g. choices of colours for the main text versus quoted text and so on. It seems a choice of font face was made available, because the AFF forum font face is different to the Xenforo Standard. That is why I assumed there is a great (greater) degree of control that the mods/admin have over some styling choices that were not exceptionally difficult to change (because not all of our mods/admins are web devs themselves).
Having not used Xenforo I can't comment on how easy or difficult it is to change some of these settings, but I guess if it is quite difficult then that's nothing against the mod team as such but rather I'm incredulous at Xenforo.
I'm actually OK with the AFF default, but I say that as a personal remark and not that it necessarily ticks the boxes for some things like contrast, positioning and so on. On the latter note, I'm of the opinion that some of the feedback offered here is too scathing and is simply a negative reflex reaction to change,
but that is my opinion. The Xenforo Standard style has somewhat better contrast as far as the content goes, but it seems less "defined" (not as many clear lines - may be awkward to see where the post controls are) as the AFF style. Plus, the combination of the serif font for main content with Trebuchet MS (sans serif) with a
third font for controls is not the most pleasing for me; the choice in the AFF style to stick to one font face for everything sits a bit better.
Maybe Xenforo would have been wiser to add at least one more default style which is higher contrast, e.g. monochrome, complementary colour scheme, etc.. I suppose if you were technically able enough, you could also write a GreaseMonkey script or similar to modify the CSS on AFF to suit your own tastes.