can't find where the difference is between 2 sites

Hi there, I have two sites:

the good one:

the problem one:

The problem one has to look the same as the good one. But font and width of the main content is different.

Both have the same settings in website styling -> fonts, but the font is different (should be Open Sans)
And the width of the main content is different from the good site. (it’s on both sites 1/5 blank, 3/5 content, 1/5 blank.)

I have checked the the custom css, but there’s seem to be a problem.
Any suggestions?

Thanks!