Wells Sub Nav Second Column

Hi everyone,

Trying to mimic an effect in a WP site on a SQSP site. 

I'm using Wells 7.0 for the side nav, but am trying to have the sub-links from folders be an addition side column rather than an accordian style. So the main nav is the "left column" and the sub nav would be "right column". 

Here's the WP site that has the desired effect using lists: https://www.annhamiltonstudio.com/projects/projects.html

& here is the site I'm working on: https://dachshund-mayflower-zreh.squarespace.com  -- pw: LWD

I'm playing around with blog posts, but I'd rather it be integrated into the nav/subnav.

Bonus if you can help me mimic the hover effect on the sub nav that is mimicked in the project thumbnail. 

Thanks in advance!