<WPG2> tags in a post

I've spent the last week or so re-writing my website to have WordPress 2.3.1 and Gallery 2.2.4 on it. I've installed WPG2 3.0.2 to integrate Gallery into Wordpress, and it looks very good too.

I have one item left puzzling me, when I write a post in WP I click the "WPG2" button and insert the images I want. I'd like these images to appear in-line with a small gap between each image, and maybe to have the images in a grey background with a single pixel border top and bottom so it looks the same as the Gallery.

Does anyone know how to do this please - which css should I update, and how?

Many thanks for your help, happy new year!