Hi Kelly - I have a screenshot to share with you. I did try to share the application but my organisation won't allow it. Perhaps when we launch it with some of our live maps I can send you a link.
It is not a huge departure from the basic template, but it has taken on enough of the look of our organisation's website that I am quite happy with it.
I managed to work through how to change colours, shapes and fonts easily enough, but struggled when it came to positioning and responsiveness for mobile/tablets. I taught myself CSS from some entry level courses on Lynda.com, and I think I will continue with some of the more in depth courses when I have the time.
Overall I am very happy with the added functionality of custom CSS. Especially due to the fact that I do not have server space available to me in our organisation, so all customisation is limited to what is provided in the app builders.