Default dock background color doesn't make it clear that the Files app is open

[moonmehta]

Check screenshot with default white plank:

And now a dark plank:

It is only clear in the dark plank that the Files app is open and not visually distinguished on the white dock.

The reverse is true for the terminal app.

Considering the Issue #39, it might be a good idea to do some minor changes to the way open applications are visually conveyed on the dock.

[danirabbit]

The plank theme is shipped in this repo. Can you open an issue there instead?

Closing for default-settings because it can't be fixed within the scope of this repo

[moonmehta]

Done: https://github.com/elementary/stylesheet/issues/323 :)