Does this FAQ work with these revisions? What needs to be changed/removed/added in? Does it still need a Modify Journal link (which was in the cut paragraph)? Is that last paragraph even necessary in an FAQ about customisation causing a journal to stop displaying? I left it in because while I can speak confidently about the styles stuff, I can't about the web-like information in that section, but hopefully someone can comment on it.
If you customize your journal using overrides and it then fails to display or only partly displays, this is probably due to incorrect CSS syntax in your overrides. If you include
<style> tags or opening comment tags (<!--) without closing them, your journal will not display. You will need to ensure that any <style> tag or opening comment tag that you use has a corresponding closing tag -- </style> for <style> tags, and --> for comment tags. This FAQ provides examples of CSS with proper closed tags, and explains basic CSS syntax. It also gives solutions to other common problems with overrides.
It's also possible that your journal is temporarily displaying incorrectly (or not displaying at all) because of high load on LiveJournal's servers. If this is the case, waiting a few minutes and refreshing the page should cause it to display properly.