I know you haven't been active since May, but on the off-chance you check this, I wanted to let you know I'm interested in implementing your proposed change to MediaWiki:Common.css as described here. I had a little mess around to try and implement it myself but tbh I have little idea what I'm doing. Got the width right, but couldn't get the diving bar to move. Just leave me a message here or on my own talk page if you're interested.