New
#1
Hi, if it uses a standard frame, then Aeroglass (free + watermark or 2 or 3 euros donation for a couple of reusable licences gets you nice borders for all but programs which use borderless windows (e.g. a lot of multimedia progs).
Aero Glass for Win8+
(That's Kingsoft writer - I don't use Office.).
Yes, I know about aeroglass by bigmuscle. It does not alter Office 2013/2016. This result in the image I posted suggests that it is possible though.
Unfortunately not all programs observe the same standard. If you look at the aeroglass site you will find support via an MS forum where you could check for comments on Office or ask a question.