How can I solve a problem "object doesn't support property or method 'getComputedStyle'" ?

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C#

Javascript

.NET

HTML

I have used a javascript code in my htmlpage where getComputedStyle has been used. It works excellent and help me to find out the css easily.

But there is a problem when I want to run this script using webbrowser from serverside. It shows a meseage : object doesn't support property or method 'getComputedStyle'.
I am using IE version 11.0.

This is my sample code:

private void test_Click(object sender, EventArgs e)
        {

            webBrowser1.AllowWebBrowserDrop = false;
            webBrowser1.IsWebBrowserContextMenuEnabled = false;
            webBrowser1.WebBrowserShortcutsEnabled = false;
            webBrowser1.ScriptErrorsSuppressed = true;

            var content = webBrowser1.Document.InvokeScript("GetStr", new String[] { "div2" });


        }

Please give me a solution as soon as possible otherwise I will miss my deadline !