Go to Appearance -> Customize -> Design options -> Custom CSS and paste the below CSS code and Click on Save & Publish button at the top of the options panel.
It works but not totally as expected.
The text spreads on a narrower width than with the wide layout.
Do you know what parameter to tweak to adjust this?
It still does not get as wide as the wide layout (and as with the additional width: 90% I put).
I did not see any major side effect so far with the additional width: 90%.
This does not mean I won’t eventually.