Google Code-in

This task is about MediaWiki's Timeline extension.

It uses the HTML tag <tt> which is deprecated in HTML 5 for error messages: https://github.com/wikimedia/mediawiki-extensions-timeline/blob/094c0a81210bb44187876ce251dc5a014d0f97d6/Timeline.body.php#L155-L187

This should be removed.

You are expected to provide a patch in Wikimedia Gerrit (not Github). See https://www.mediawiki.org/wiki/Gerrit/Tutorial for how to set up Git and Gerrit.