Customizing Ghost Post Theme

I have been converting my static website over to a static theme this weekend and I have most of it done, but I have questions about converting the Post page.

Ghost has many different post modules and such. I have pulled in the content through the {{content}} tag, but it doesn’t look so great. I want to alter it but I don’t even know where to start. How do I cover all of the different Ghost modules? Is the only way to go through every single module and test it?

I would love to just use a current post theme (such as from Casper), but when I do that it messes up the CSS of the rest of my site due to conflicting attributes. Any idea for me?