Change Bueno Theme Width

I really like this Bueno theme ( https://ww.wp.xz.cn/themes/bueno ), but the full page width is just too wide. I’ve tried a few Custom CSS lines, but it either chops the sides off or puts the content box in a strange location. Is there a way to add more padding on the right and left to make it look less wide on larger screens? Thanks.

Example: http://tonybabecka.com/wordpress/

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