Rouge also forgot, but quit VisualEditor. This editor creates very messy code, adding to this it also breaks some templates (hopefully on the page you edited it didn't break anything, it just did a bunch of messy code).
Go on your preferences page, on "Modification" tab, go on the first menu. It selects the editor per default for editing. You have three choices: VisualEditor (the one per default for all new users), classic editor (or rich text editor) and source editor.
I first advise you to begin by classic editor. It does less code corruptions. The only thing it may do, it's just turn <br> into <br /> (we rather the 1st variant), but it's the most user-friendly. Otherwise you can directly go with source editor, which guarantees a total absence of unwanted code changes, but possibly requires you either to know wikicode very well, either to have a manual next to you ^^"