Is there a way to fix this particular issue in Cadence? Image below for reference

Your portal mod is messing with the layout. It wraps the stuff in `#main_content_section` with a table structure `<table id="sp_main">...</table>`.

That portal mod was not designed with the Cadence theme in mind. Also the Cadence theme was not designed with that portal mod in mind.

The portal mod you are using looks like some trash. It just puts everything in table elements. Using tables for layout has been a big no-no for a long time now. See this wikipedia article.

Gotcha.  Which Portal Mod would you recommend then?

Gotcha.  Which Portal Mod would you recommend then?

I personally have never used a portal mod. I always use custom external pages. You can see how to set it up in this thread: http://visualpulse.net/forums/index.php?topic=296.0

I am sorry I can't recommend one but I just have no experience using portals. My overall opinion from exposure to portals,  from questions like yours, is that they cause more problems than they solve. My recommendation is to learn how to do the custom external page(see thread linked above).

  I disagree with your statement regarding the use of HTML tables whereas at times they still have their place. The template in topic here will actually make it impossible to add any content on the left or right of the current display while using existing common SMF css classes. This is due to this template's 1000px and 950px title & catbg widths being used that stretch to the far right without any aesthetics to the right edge of the graphic used (because it extends to the end of the screen).   Even without tables, I do not think any portal side blocks/modules will appear correctly using this theme.

Btw, even the wiki article you linked states that tables still have their place:

There is still (as of 2011) some distance to go; some web developers have yet to remove the tables from their page layouts, while others are now afraid to introduce a simple HTML table even where it makes good sense, some erring by the overuse of span and div elements, perhaps even with table-like rules applied to them using CSS

HTML tables still have their legitimate place when presenting out tabular information within web pages.

Stating that one of your peers modifications was trash is very disrespectful.
That portal is currently the top rated one for SMF and has been for quite some time. 
Simple Portal is the #1 most popular and #3 most downloaded mods of all time.

The theme in topic here is also void of a category collapse and has the admin display toggle disabled, was that on purpose?

Regards.

Btw, even the wiki article you linked states that tables still have their place:

HTML tables still have their legitimate place when presenting out tabular information within web pages.

To clarify the statement. I said that it is not the way to do things when it comes to site layout but they are still good to display data semantically. This is a fact of web development today that is well known.

There are lots of ways the portal peoples could do the layout:

• Float Demo
• Inline block Demo
• Flexbox Demo. My new favorite(not exactly fire-proof cross-browser wise though).

I may have stated my opinion of the mod a little harshly, but I am not a proponent of portals at all, no matter how popular they are. It is a really bad CMS that is super cookie cutter.

Pulse was my very first theme released. I realize that there are many flaws with all three of my themes. Those themes were made 3 years ago and I have grown as a developer working on other projects and just haven't had the time or desire to go back update them to my new level of standards.

I continue to give support to these themes and have no problem helping people fix the problems.