Custom Tip with image

Summary:

I'm trying to create a custom smart tip with an image. I've created its own CSS rule as detailed on and its pulling though, however when ive added the image, its still coming up as a circle rather than the image. IS there some additional code i need to add so the image size pulls through rather than the circle? Image one is what is showing, image two is what i want it to show. Thanks in advance.

Version (include the version you are using, if applicable):

24A

Code Snippet (add any code snippets that support your topic, if applicable):