As an alternative to a corner window for the top floor home office, a different idea, that could make the top half of the office floor look as if it’s lighter, but it floating, is a side slot:

This idea could be extended / used on all 3 floors of the building or just the top office.
– if used on all 3, the slot could be the longest / deepest on the top office floor.

A corner slot would mean less glass, which means better insulation (walls are better than windows for insulation) and lower cost.

(The pictures are from houzz.com.)