Hi Simakki,
thanks for using MH Squared lite.
How i could edit main sidebar width
That isn’t possible out of the box. But if you are familiar with coding, you could create a child theme and modify the theme as you like.
background color?
You could change the background color of your site in your WordPress dashboard under Appearance => Background.
how come my two “post” have a different font?
That question can’t be answered without actually seeing your site.
Have a nice weekend.