Here is an example of MacStories Shortcuts Icons in action ... Rosemary Orchard MacStories Shortcuts Icons are not just a random icon set: each icon was specifically designed with a potential use case ...

MacStories Perspective Icons are the ultimate set of custom perspective icons for OmniFocus Pro. Specifically designed for OmniFocus Pro and spanning dozens of categories, Perspective Icons will let ...

You can set a dark or any icon of your choice – but the images have to me in the .ico format. Read: How to change File and Folder Icons. As an example, let us change the icon to a dark one.