Maximum width for sections on a page

Freely flowing text becomes harder to read as the width of the browser increases.  I want to limit how much a section on a page can grow in width.

I want to specify a maximum width for sections, and have those sections center justified in the browser window.  If the browser window width is shorter that the maximum width specified for the section, the section must honor the browser width.

There may be diagrams on the page that may need to be wider.  These can be put in a section of their own, and that section allowed to match the width of the browser at all times, i.e. maximum_width set to 'ANY'.

I am not referring to Section & Column macros here.  I am referring to the page layout tool and the sections that can be added with it.

I was able to achieve the maximum width setting using HTML macro by using <style>, and setting it for .columnMacro.conf-macro.output-block, .cell.normal.innerCell, and .columnLayout.single.  But it is just a hack.  A Confluence native solution is desirable.

Using stylesheets is not an option for me because creating a new space to apply it is not something I decide or control in my company. I can only control individual pages. In fact, my company has actively refused to create separate spaces for projects for various reasons.