Sorry but since öl is a -n word why is it "ljust och morkt"? Am I missing something?
It can actually be either, depending on what you mean. ett öl is for when you're talking about a specific beer, and en öl is for when you're talking about an amount such as "a beer".
is this specifically for the word öl or does this apply for every noun in Swedish?
It only works for a few words, öl being one of them. Another is vin. I think there are a few more but I can't come up with any at the moment. :)
I'm a Swedish native and I've quite literally only heard "ölet" when I've spoken to friends about whether or not it is proper Swedish to say it. If I was talking about beer as in "that beer" i'd say "den (där) ölen" and if I was talking about a brand of bear of a kind of bear I wouldn't say "det ölet" (even if that is proper Swedish, you basically never hear it), I'd still say "den ölen". "Den ölsorten" (that kind of bear) would be fine too.
An ale is just one type of beer, though - and one which we call ale in Swedish as well, with the English pronunciation.
or are there different words for "lager" and "ale" and öl is just "beer"?
It's actually pretty much like in English - you can use öl for any beer, or you could specify a lager or an ale - we even use the same words. :)
lager uses standard Swedish pronunciation, ale uses English pronunciation.
As a proud member of CAMRA I didn't think for a moment that this sentence did not mean light and dark as light coloured and dark coloured. If someone just asked me to translate "light beer" into Swedish there would be a problem, as in this case there is certainly a possibility of "light coloured" and "weaker". By the way, how horrible is the term "lite"? Something I'd run a mile from!