CSS question on HTML site with WP blog

I am working on a client site (SteinersJewelry.com). It is an HTML site (created by someone else) and I had them install a WP blog at http://steinersjewelry.com/jewelry-blog/ so that I could add content for SEO purposes.

My issue is with the .css of the blog. The developer created a look/feel of the original site, but the blog posts have no formatting (e.g. the line breaks run together and the image alignment isn't acknowleged/reflected in the post).

Is the WP blog looking at the wrong .css file (maybe looking at a .css for the core site) ... or is there a way that I can use some sort of 'default' .css to make the blog post look nicer? I'm just looking for the very basics - basically just the two items listed above to be resolved.

Thanks in advance for the help.