By now most folks that are dabbling with HTML5, CSS3 and Responsive Design in SharePoint will undoubtedly come across some issues with the fact that IE9 and SharePoint don’t (yet) play as nicely as they should. In fact, there is a META tag in the V4.master, master page forcing IE9 to succumb to IE8 standards.
If you are having issues with your SharePoint Deigin while experimenting with these newer technologies, try starting with your meta tags:
You can change this content= to thiings like IE=9 or Edge. Learn more here: A List Apart