If I choose the Windows theme from Windows Default Themes or Windows Installed Themes, I get a think border on windows, but it's transparent.
I got the aerolite and aerolite (white-text) themes from Aerolite Theme - Install in Windows 10 - Windows 10 Forums. Both of these give me solid borders, but the text of my clock system icon is black. The white-text version still gives me black text.
I notice that the High Contrast themes give me thick colored borders and white text. I don't want to use these, but I mention this to give someone possibly a clue as to how to make things work.
The black text came with the windows update that I installed today (Sept 22).
So I'd like to see:
(1) a way to remove the window border transparency without affecting other properties,
(2) a way to set white text without affecting other properties,
or (3) posting a theme file that has colored borders and white text.
BTW, I wonder if the .msstyles files have something to do with this. I think I downloaded aero\aero.msstyles and aero\aerolite.msstyles in July, they are dated 7/16/16. But I saved an older version of these, dated 10/30/15. This was before I upgraded from Windows 7 to WIndows 10.