Help with Width text area in post pages

I am using the mantra theme and two sidebars layout, I got no problem with the width in pages, but the width in the text area of the posts are as wide as the author and date bar, leaving a empty white space

I have been trying with some css but it does not work, could someone give me some hints to solve the problem, by the way i am using a pluging to hide author, date, categories, not sure is that could be the problem, anyway pages have a normal width

.single-post .container{max-width: 100%;}

.single-post .content-main {padding: 4% 0px !important;}

• This topic was modified 6 years ago by Zed. Reason: moved to correct forum