How to decrease width of right sidebar

I have seen a blog layout I like on a theme from the enfold showcase.

Here: http://hotspotcreative.ca/edmonton-graphic-design-blog/page/2/

The first thing I am trying to do is decrease the width of the right sidebar in the default theme.
I found this post by Devin https://kriesi.at/support/topic/changing-sidebar-width-2/#post-134647 which looked promising. But when I went to make the suggested changes in functions.php , it seems the code has since been replaced.

Devin’s code from 2013:

$avia_config['layout']['fullsize'] 		= array('content' => 'twelve alpha', 'sidebar' => 'hidden', 	 'meta' => 'two alpha', 'entry' => 'eleven');
$avia_config['layout']['sidebar_left'] 	= array('content' => 'nine', 		 'sidebar' => 'three alpha' ,'meta' => 'two alpha', 'entry' => 'nine');
$avia_config['layout']['sidebar_right'] = array('content' => 'nine alpha',   'sidebar' => 'three alpha', 'meta' => 'two alpha', 'entry' => 'nine alpha');

Current code in the functions.php

$avia_config['layout']['fullsize'] 		= array('content' => 'av-content-full alpha', 'sidebar' => 'hidden', 	  	  'meta' => '','entry' => '');
$avia_config['layout']['sidebar_left'] 	= array('content' => 'av-content-small', 	  'sidebar' => 'alpha' ,'meta' => 'alpha', 'entry' => '');
$avia_config['layout']['sidebar_right'] = array('content' => 'av-content-small alpha','sidebar' => 'alpha', 'meta' => 'alpha', 'entry' => 'alpha');

So i can’t simply change the units , ensuring they add up to 12 now.

Can you advise how I can change the width of the right side bar, so that it retains its responsiveness. I want to make it a bit smaller.

Also can you give me any advice or pointers about how I might go about getting the same blog layout to the example I posted at the top of this request for support.

Many thanks

Spleeky.