Put a very thin gray border around the main window frame
Put a very thin gray border around the main window frame when running Dark Theme so I can find the bottom corners on top of other "dark mode" things, like Windows Desktop (black), Notepad++ (dark theme), etc.
Yes, please add a border (or an option for a border) for all themes. The lack of a border causes the window to blend with everything making it very difficult to identify where one program window ends and another begins.
In addition, consider adding an option for the theme in Teams to follow the theme in Windows!
J Vojtisek commented
Yes, please add a border around the main window. Actually I think it should not be a "thin grey boarder" but a standard windows border which I can configure in my OS and which would look the same for all my windows application. IMHO that should also include the minimize and maximize buttons.