window background is suddenly brighter and no guides are visible

[default4a1g3fiil39y]

I must have pressed something, because now I cannot see any guides nor margins, and the background is a lot brighter (from the orginal dark gray). I thought this was overprint preview at first, but toggling it on or off has no effect. Is this some viewing mode that I'm unaware of? 

[default4a1g3fiil39y · Accepted solution]

Turns out I was using "View > Screen mode > Preview" instead of "Normal". Is there a difference between overprint preview and preview?

[Frans v.d. Geest]

Yes. Preview is a view without guides, margins, hidden characters and frame edges; Overprint preview is a colour preview, that accurately shows colours that overprint or transparency blend view; Overprint preview can be used in Normal as well as Preview mode 😉