after mx developers showed their css skills on April 1st,
they might conisder to make such nice things.
any more css Ideas?

Sure we have some CSS skills, but why do you need a bigger version of the preview screenshot when you click it?
If you click the trackname, it'll show you the bigger screenshot.

If you mean bigger than on the track page: that's not possible - it's the size people upload to the site.
Changing it might proof difficult, as it's being used on other sites too.