Control Panel - under Ease of Access select "Optimise Windows display".
"Under Make things on the screen easier to see" click on "Adjust the colour and transparency of the window borders".
Click on "Advanced appearance settings" (at the bottom).
Under "Item:" It defaults to Desktop but you can select from many different items including Window. You have a choice of colours for pretty much everything.
You can also change Font, Font size and Font colour in the Active title bar.
It's interesting to experiment to see what suits you - you can always change it back if you don't like it.