During last weekend I already teased a web part named ‘Panthema’. I was a bit surprised by the interest in this helpful tool for developer, consultant and everyone who has to manage themes in SharePoint on Office 365. I also think it helps a lot in debugging the colours used.
You install the web part solution to your tenant and change the theme. The web part shows you then all used colours by this theme. A hover over the cards shows the theme slots used.
Have fun with this helpful tool, please provide feedback there are some things I add to it in the near future.