I used reddit-inline for a while and started a similar project reddit-ng.

Hi you might want to try: https://github.com/ayurmedia/reddit-ng , demo link is in my github project.
It uses a similar idea, but not as a chrome-plugin, but standalone Javascript. It uses a popup-window to display the reddit-post-content. The popup is not an iframe, so things also work.
My Version has a slightly different approach to show the list of comments in the right bar, and use a next-button to skip from one post to the next. i tend to read all posts in a list, but use subreddit filters to hide some stuff i dont like.

Start by reviewing the linked reddit-ng project and comparing its standalone JavaScript popup, comment sidebar, next-button navigation, and subreddit filters with reddit-inline. The issue does not identify files, tests, or a specific change, so a concrete scope and definition of done would need to be established first.

Written by the indexing model from the issue text.