Based on current demos and feedback received by users here are some proposals to make more space for content and make it easy for user discover what Seed main features are about, backlinks, link anything, comment anywhere.

Main changes to Make more space for content

Make main header smaller (from 80px to 64px)
Add a secondary header with breadcrumb and main CTA including search to easier find (we need to improve search experience, but in general search is not something users see)
Move up all the content area, covering more the image cover if there is
Move create by to the bottom together with created by Seed (I propose to make it sticky). Seed needs to be easier to see, other tools use there brand as umbrella, we are quite invisible to users when they come to read.
Move navigation items closer to the logo

Main changes for discoverability / still defining but some ideas

Treat the home page as a different page. This is the main page where user needs to be guided. Admin needs to add an intro to the space and a summary.
Remove activity tab and merge into one section for latest activity prioritizing references, comments, mentions...
Use bottom area to show people's activity: Eric Vicenti, Bea, Gabo are contributing on this

Some sketches

Notes from Gabo: Layout Problems and Improvements