I don’t understand. If the top banner were too high, then wouldn’t that mean there is more space for the main contents?
By Top Banner, are you talking about that thin strip which has the logo on the left and the search icon, hamburger menu and your avatar on the right end?
Yes, I meant the strip was too high.
Edited: To add, the “F” icon on the right side of the strip might be too small since that F icon is sometimes the only link to go to the top page (index page?) in the page.
Edit 2: The strip can be an auto-hide element, like the one on google +. Here is an example of Google + auto hide top strip.
https://plus.google.com/101922061219949719231
Thanks for clarifying. I do plan to enlarge that F logo. I am literally using a very crude version of it. You might recognize it as the old forum’s “favicon” and even among favicons, it is the smallest kind (only a single 16x16 layer).
I also agree that getting from a topic to another category or subcategory can be cumbersome. I like the “related topics” list at the bottom, but many times, I want to just go to another part of the forums. I am still getting used to the jump menu in the bottom right corner, and it isn’t intuitive for me.
Are you saying you want that top strip to disappear altogether when you are reading the topic?
Are you saying you want that top strip to disappear altogether when you are reading the topic?
Yes, I meant that. Both when reading and scrolling threads.
In case of Google+, it hides the strip when certain amount of page is scrolled down so that viewers can use the full screen.
There is an old thread that can not be opened when logged in:
Not sure if this is just a rare anomaly. 
I just opened it, not sure what you mean?
Ah, happens on latest Firefox v68.0.1
I did a forced reload (Ctrl + F5) and now it works.
I think it was some encryption protocol mishap which remained in my browsers cache.