Varied Views on Different Browsers

I am working in the site and using Chrome and Mozilla to view the end result......   How can this issue be fixed? See photos for issue..... First photo is how Mozilla looks when the site is set (kind of) to fit Chrome (2nd Pic) and then 3rd what Chrome looks like when the site is set for Mozilla.  And why do I not see this issue ANYWHERE else in the website world? I use Homestead Sitebuilder on a desktop and have always used Mozilla as my viewing browser until recently when Google dictated httpS.