It appears that you've applied a global padding to ULs, and that breaks the way the menu displays. It also appears to have changed the positioning of the buttons for Tab Show.
You'll need to change the UL style around line 8 of editor.css back to what the original code was.
If you really want to add padding to ULs in your content, you can use the following CSS:
#s5_center_column_wrap ul {padding:13px;}
Just make sure that any CSS you change to style content has that ID in front of it, and it will only apply to the content area, instead of breaking things elsewhere on your site.