We already checked your website in IE11 but also don`t see any issues except icons that are not visible. But this problem is not related with theme but with server settings. Take a look at http://snag.gy/Rc6FB.jpg please. As you can see, requests for fonts are blocked by server and this should be fixed by hosting provider.
Also please open your website in Firefox html mode (CTRL+U) and check how many html errors you got. Those html mistakes should be fixed as well.
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Also please open your website in Firefox html mode (CTRL+U) and check how many html errors you got. Those html mistakes should be fixed as well.