I have a SharePoint 2016 page based on Seattle.Master. Empty of content, it displays correctly: the top level navigation bar is centered across all monitor resolutions. But the moment I add custom content (nothing fancy, just a bunch of divs) inside the following tag the top level-navigation moves all the way to the left of the page. I've tried fixing the width of s4-workspace to 1100px, but the top level navigation always moves to the left, or the right.
Does anyone have a solution? Most of the more popular using fixed-width don't seem to work.