Thread:Talk:Download/Class=mediawiki dont work correct/reply

MW 1.9 is 5 years old. Did you mean 1.19? -- I don't believe we have a css class named "mediawiki" (although I could be mistaken). Are you sure its not a class you yourself added?

If any css files in the skins subdirectory were modified for custom styles, they will be overwritten during an upgrade. Any custom CSS should be in the page MediaWiki:Common.css on your wiki in order to be safe from upgrades.