hi am new in ext.net am using master page with view port. and am using this master and create tabpanel it wont take full width

[antoreegan]

this is may master page
pl

<ext:Viewport ID="Viewport1" runat="server" Layout="FitLayout">
        <Items>
            <ext:Panel ID="Panel1" runat="server" Layout="border" Border="false">
                <Items>
                    <ext:Panel ID="Panel4" runat="server" Region="North" Height="75" Layout="FitLayout">
                        <Content>
                            <asp:ContentPlaceHolder ID="ContentPlaceHolder3" runat="server" />
                        </Content>
                        <BottomBar>
                            <ext:Toolbar ID="Toolbar1" runat="server">
                                <Items>
                                    <ext:Label ID="Label1" runat="server" Text="Home" Icon="House" />
                                    <ext:ToolbarFill ID="ToolbarFill1" runat="server" />
                                    <ext:Label ID="Button5" runat="server" Text="Welcome User" Icon="User" />
                                </Items>
                            </ext:Toolbar>
                        </BottomBar>
                    </ext:Panel>
                    <ext:Panel ID="Panel2" runat="server" Region="Center" Layout="VBoxLayout">
                        <Content>
                            <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server" />
                        </Content>
                    </ext:Panel>
                    <ext:Panel ID="Panel3" runat="server" Width="200" Region="West" Layout="Fit" Title="Navigation"
                        Resizable="true" Split="true" Collapsible="true">
                        <Items>
                            <ext:Panel ID="Panel6" runat="server" Layout="Accordion">
                                <LayoutConfig>
                                    <ext:AccordionLayoutConfig OriginalHeader="true" />
                                </LayoutConfig>
                                <Items>
                                    <ext:Panel ID="Panel7" runat="server" Title="Item 1" Border="false" />
                                    <ext:Panel ID="Panel8" runat="server" Title="Item 2" Border="false" />
                                    <ext:Panel ID="Panel9" runat="server" Title="Item 3" Border="false" />
                                    <ext:Panel ID="Panel10" runat="server" Title="Item 4" Border="false" />
                                    <ext:Panel ID="Panel11" runat="server" Title="Item 5" Border="false" />
                                </Items>
                            </ext:Panel>
                        </Items>
                    </ext:Panel>
                </Items>
            </ext:Panel>
        </Items>
    </ext:Viewport>

this s my children page

<asp:Content ID="Content4" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server"
    style="width: 100%">
    <ext:TabPanel ID="TabPanel2" runat="server">
        <Items>
            <ext:Toolbar ID="Toolbar1" runat="server">
                <Items>
                    <ext:Panel ID="Panel2" runat="server" Region="Center" Layout="VBoxLayout" AutoWidth="True">
                        <Content>
                            <ext:Label ID="Label1" runat="server" Text="Home" Icon="House" />
                            <ext:ToolbarFill ID="ToolbarFill1" runat="server" />
                            <ext:Label ID="Button5" runat="server" Text="Welcome User" Icon="User" />
                        </Content>
                    </ext:Panel>
                </Items>
            </ext:Toolbar>
        </Items>
    </ext:TabPanel>
</asp:Content>