In the Opera browser, Linux and Win XP where I have tested this, the New "Parameter" theme makes a move, or shake the whole page when you hover the mouse around a link.
Using both; Theme and Child. When the web page refreshes in this browser, it leave a margin at the top of the title, then moving the mouse for any link the page is shaken and returns the top margin.
Remove all hover, and color without overcoming the problem.
The strange thing is, I assign a page to archive a section on child theme (a new archive page), in this particular section this error does not happen, trying to do the same with other page, the error is not eliminated.
I'm about to give up, someone here has had the same experience, or any recommendation to try.