JQGrid header height

Question

I am using JQGrid within an ASP .NET MVC application. The grid itself is working great. However, the header height of the grid (or first grid on the page) is growing to match the height of my left navigation menu. Here is most of the Site.Master layout that I have. I just don't see why this is happening.

<div class="page">
        <div>
            <div id="left">
                 <div id="leftnavmenu">
                       <%= Html.MvcSiteMap().Menu("MvcSiteMapProvider", "activenav")%>
                </div>

                <div id="leftnav-msg">
                        Message goes here
                </div>
            </div>

            <div id="main">
                <div id="mainsitename">
                    <div id="mainsitenameimage"></div>
                    <div id="mainsitename1">Intake Tool</div>                
                </div> 
                <div id="mainpagetitle">                 
                        <%--<%=Html.MvcSiteMap().SiteMapPath(" &gt; ") %>--%>
                        <asp:ContentPlaceHolder ID="PageTitle" runat="server" />
                </div>

                <asp:ContentPlaceHolder ID="MainContent" runat="server" />

                <div id="maintabledata">
                    <asp:ContentPlaceHolder ID="TableContent" runat="server" />
                </div>

                <div id="footer"></div>
            </div>
        </div>
    </div>