Try disable the Windows 10 drop shadows, click the Desktop Start Button and type Advanced System Settings. Click on the result that says "View advanced system settings." Alternatively, you can navigate to this same settings window by going to Control Panel > System and Security > System > Advanced System Settings.
Under the Performance section of the Advanced tab, click Settings to open the Performance Options window. There, under the Visual Effects tab, find and uncheck the box labeled "Show shadows under windows." Click Apply or OK to save the change and close the window. As soon as you do, all drop shadow effects will be disabled, giving you a truly flat user interface.