Problem with Perch on a One-Paged Blog

Hi all together,

I'm new to perch and so far I'm very happy with it, besides this one question that I cannot solve for days now.

I'm using perch blog as a cms for a one-paged blog, that is split in two parts: On the left you have the list of posts that you can filter by categories and on the right you have the posts itself (see attached screenshot) or check this link: http://blog.h4u5.com/blog/index.php

Whenever I am clicking on a post-link on the left, the correct post appears on the right half of the screen and whenever I am clicking on one of the category links on the left, the post-links get filtered correctly. Right now I gather my categories, my post-list and the post in the same index.php (I am not using archive.php for categories for example) as I want it to be a one pager.

My problem is the following: If I click on a category link to filter the post list, the current blog post on the right disappears. I would like it to stay, ergo: to display category and post at the same time.

What I am looking for is a possibility to filter categories/ navigate on the left half of the blog, while keeping the current blog post displayed on the right.

I tried many things but so far this seems the most promising solution:

If I would have my url always structured like this: index.php?s=name-of-blog-post&cat=nameofcategory I would get the post slug AND the category slug displayed at the same time and somewhat independent from another. Whenever I would filter the categories just the second half of the url (behind the &) would get updated and the current post (first half of the url) would just stay on display.

The problem is: I don't know how to achieve this. How can I tell the category links to not only get the requested category, but also keep the current post on display (and reflect that in the URL)?

Or do you think there is an easier way to achieve this, for example with somehow using only one template for everything? Or something completely different?

I would be so happy for any help!

Thanks so much!