Login appears behind other elements with some themes

Hi – I love this plugin. It gives a nice professional feel to my sites.
Since the last couple of upgrades, however, the modal login box and grey overlay have started appearing behind some elements of my sites, particularly with the Nirvana theme from Cryout Creations. They set the z-index of their #topbar item to 270 or so, and for the logo image to 9996.

The fix is easy; I edit widget/widget.css and under /* Modals CSS */ I change the z-index for .lwa-modal-bg to 9997 and for .lwa-modal to 9998.

I get tired of editing widget.css with every upgrade and for every site, though. Is there a chance of making the z-indexes something really big so the overlay and modal are always an overlay, regardless of the theme used? Say around 50000 and 50001?

https://wordpress.org/plugins/login-with-ajax/