So, you've given your best shot and correcting all compatibility issues on your website to make it function properly in IE 9. But, it was just too overwhelming.
Luckily, there's a bit of a shortcut, which allows us to force the user's web browser into IE 8 rending mode.
Just drop this handy little meta tag in your header and voila – things work again!
<meta http-equiv="X-UA-Compatible" content="IE=8" >