Need help with Fluid Grid Layout and variable column balance.

Question

I'm using the fluid grid layout.  I have multiple columns that are actually fluid grid layout columns done by Dreamweaver.  I'd like them to extend as high as each other (all to the maximum height of each other) within the same section.  An added catch is that in the desktop layout, I have three side by side under one that takes the whole width of the page.  On tablet size, it's 2x2 in a square grid.  On mobile, they're vertically stacked.  I'm trying to get it so that background colour and/or borders looks decent and is fully balanced, no matter which layout is hit with the fluid layout.  The columns reflow, no problem.  But the height of any background and/or border is variable. 
Any help on fixing this? 
Example at:  https://music2help.thoughtburst.net/ 
The example doesn't have borders or colours, as it looked silly unbalanced.  The music2help.css is the only one I'm modifying manually.
Love the fluid grid layout, but I need a way to make it behave decently with backgrounds/borders.  Any help would be hugely appreciated!
Thanks!
mark->

Answer 1

I tried the solution Nancy posted.  It altered things, but doesn't seem to do the trick.
Just some quick background.  I did HTML from 1994 through about five years ago by hand in vi on *nix systems.  I learned HTML through 4.01, and never bothered with XHTML at all.  I learned CSS through most of CSS2.  The CSS3 and HTML5 stuff is all new to me, but it can't be that hard.  I'm not exactly a novice in JS (I've done a fair bit of AJAX programming), but it's not even close to my primary language (I'm a Perl guy).
I'm "stuck on" wanting to use Fluid Grid Layouts.  It's billed as one of the selling points of DW CS6, and I really like the concept and results.  I just want the results embellished a little, namely with sensible identical heights on grid containers set in the same row, so that you can apply background colours, dropshadows, and borders.  That's really all I want to do that it doesn't already do.
I have a test page at:  http://music2help.thoughtburst.net/ that you can try with your Quick Columns.  I'd be interested to know if you can get it to work.
Here's the catch, though...  Resize the browser, shrinking it inwards.  (I suggest Firefox, as Chrome only shrinks so far, and you won't get to Mobile width.)  As you can see, on a Tablet, one of the columns that should be equal height actually moves up a row and should be equal height with the row that, on a desktop, would take the entire width of the page area.  So that's like a 4-up output in printing terms.  At Mobile size, the entire thing is vertical, so none of the columns should be resized.
If your product works and can accomodate these conditions, I think I would be interested in spending the $35 it costs. 
Let me know?  Thanks!
EDIT:  Changed URL to be non-SSL.  The server has multiple vhosts on it, and I keep forgetting that I don't have a cert on this new one.  Sorry about that.  You can just add anything to one of the the three middle columns, if you're pulling it down to test.