Suddenly my top menu has stretched to 1594 px

Yes, the inline style is added by the code.  There should be no inline style added to the menu table. It sits in a division that is set to the width you have set for your pages.  The topMenu then controls the layout of the table.  I would check the template files to see if somehow it got added to the template.

check your site's width and page width.

I am guessing you hit the slider for "other pages width" in the page builders.

All the pages are set to 998 in the builders>pages block, the page content  itself is 998px. The header is way too wide. I just noticed that the footer is the same width, 1594px.

What could affect the footer and header but not the content of the page?

There are two sliders in the page builders. The one at the very bottom under the samples section is what affects the menu and footer areas.

Check again. It has to be incorrectly set. I cannot think of any other reason.

Yes, that was it! I actually never noticed that slider before. I must have hit it by accident.

Thanks so much!

Dan