The IE7/IE8 compatibility modes are notoriously unreliable, e.g.: Most importantly, why does my page not work in IE7, even though it works in IE7 mode in IE9?

The IE7/IE8 compatibility modes are notoriously unreliable, e.g.: Most importantly, why does my page not work in IE7, even though it works in IE7 mode in IE9? http://stackoverflow.com/questions/5993222/why-does-my-page-work-in-ie9s-ie7-mode-but-not-in-ie7-itself http://stackoverflow.com/questions/5993222/why-does-my-page-... IE9’s emulation of older IE document modes makes this easier but those emulations are not exact. http://blogs.msdn.com/b/ie/archive/2011/02/04/testing-multiple-versions-of-ie-on-one-pc.aspx http://blogs.msdn.com/b/ie/archive/2011/02/04/testing-multip...