Wider content area does not work

Hello,

I’m having a problem with the Wider Content Area option at WordPress 4.1.1 and Writr 1.2.1, with all plug-ins except Limit Login Attempts turned off.

It simply does not work.

Here’s what I do:

1. On default, the theme looks like this (as viewed in the Customizer with the sidebar slided away): http://hubertbrychczynski.pl/wp-content/uploads/2015/04/step-1.png

2. Then I open the sidebar back into view: http://hubertbrychczynski.pl/wp-content/uploads/2015/04/step-2.png

3. Then I choose the option: http://hubertbrychczynski.pl/wp-content/uploads/2015/04/step-3.png

4. Finally, this is the result: http://hubertbrychczynski.pl/wp-content/uploads/2015/04/step-4.png

Compare:
BEFORE: http://hubertbrychczynski.pl/wp-content/uploads/2015/04/step-1.png
AFTER: http://hubertbrychczynski.pl/wp-content/uploads/2015/04/step-4.png

No difference for me.

Anybody can help?