Making the active window more obvious in OSX

From an accessibility point of view there are many people who find it easier to control their computers by (effectively) the keyboard, rather than the mouse. One of the things that comes up semi-regularly is mistakes caused by not realising which window is the active one.

I'm looking for a tweak or even a program that makes it easier to see which window is the active one in OSX. I'd like like something that just, for example, dramatically increased the shadow, or boardered the active window in Red.

I just installed Honer and it rocks! It draws a border around the active window, defaulting to red, which makes it very obvious which is the active window!

Here's the before and after screenshots.

You can choose the colour, width and transparency of the border. It's exactly what I personally have been looking for!

You could try white on black - then the shadow becomes more of a glow. Ctrl-Alt-Cmd-8 or Apple -> System Preferences -> Universal Access -> Seeing -> White on Black.

On the other hand you can use a third-party program like HazeOver

A built in way to improve this is to adjust the macOS transparency setting.

Go to System Preferences → Accessibility → Display and check the box "Reduce transparency".