"Is it Friday today?"
Translation:Är det fredag i dag?
Yes, it’s usually recommended to write them apart and that’s what newspapers do for example. But just as many if not more write them together. Both are acceptable. Same goes for ”igår” etc.
When "idag" is also correct and a lot of the Swedes use it that way (also imorgon, ikväll,...) why is it marked as a typo? It is just a different way of writing but it is still correct. May it would be better to note it as a different way of answer??