C# UI automated testing Excel Add In button

In our project we've decided to add a button to the Ribbon of Excel. I need to write an automated test that tests the button itself as well as the form it opens once it's clicked (font, color etc). I'm quite new to this as the only testing I've done is on web pages using Selenium so far. Can I use Selenium to test this? If someone could guide me on how to proceed I'd appreciate it as I'm struggling to find information on this online.