How do I add some css to the settings page

One of the core links on the profile page is “settings”. I need to add a div tag because all the content is too wide. I could manually add it to the other pages to get content to fit, but I can’t find where the settings pages are coming from? the bp-core-settings.php file is not it. I don’t want to remove it, or change it’s function, I just need to add a div tag so it fits in my site.