As Windows 10 matures we are seeing more choices on what theme ( colour) you want to run your application in. This is a very short tutorial as the changes are relatively easy to make. The windows 10 Mail application can be changed by following the arrows in the screenshot below: The Edge browser also has options to run in the new dark mode: You'll need to click on settings arrowed above: As you can see a pretty simple process which can change the look of your browser or Mail application quite drastically. If you dislike the new look then to go back you simply reverse the procedure. If you find that you have recently upgraded and do not see the above options then chances are is that your missing a couple of updates so make sure your Windows is fully updated..