Adding Max Screen Width

Hi there, I was wondering how can I set the max screen width to, say, 1260 px? I ask this because I think the content wrapper I set to 1260 px, but when I expand the screen beyond that, some things still move/are responsive. I noticed the page title and the site header and footer areas keep moving beyond 1260 px but everything in the page stays in place. Is there a way to set a maximum screen size of 1260 px so everything stays in one place beyond that point? I don't know if this might cause problems... Thank you for your help!