how can i adjust gridview header ? asp.net c#
<p>I have a gridview which contains <code>EditItemTemplate</code> and <code>ItemTemplate</code> but <code>gridview</code> header not adjusting.How can i adjust my <code>gridview</code> header .
Here is my gridview <a href="https://i.stack.imgur.com/farxT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/farxT.png" alt="IMG"></a></p>

<p>Here is my aspx.cs code :</p>

<pre><code>&lt;asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
       Enableviewstate="False" Width="1000px" CellPadding="2" ForeColor="#333333"  AllowPaging="true" Height="400px" DataKeyNames="User_ID" onrowcancelingedit="GridView1_RowCancelingEdit" 
        onrowdeleting="GridView1_RowDeleting" onrowediting="GridView1_RowEditing" 
        onrowupdated="GridView1_RowUpdated" onrowupdating="GridView1_RowUpdating" &gt;

        &lt;Columns&gt;
            &lt;asp:TemplateField AccessibleHeaderText="User_ID" HeaderText="User_ID"&gt;
                &lt;EditItemTemplate&gt;
                    &lt;asp:TextBox ID="TXT_ID" runat="server" Text='&lt;%# Eval("User_ID") %&gt;'&gt;&lt;/asp:TextBox&gt;
                &lt;/EditItemTemplate&gt;
                &lt;ItemTemplate&gt;
                    &lt;asp:Label ID="txt_id" runat="server" Text='&lt;%# Eval("User_ID") %&gt;'&gt;&lt;/asp:Label&gt;
                &lt;/ItemTemplate&gt;

            &lt;/asp:TemplateField&gt;
            &lt;asp:TemplateField AccessibleHeaderText="Name   " HeaderText="Name"&gt;
                &lt;EditItemTemplate&gt;
                    &lt;asp:TextBox ID="TXT_NAME" runat="server" Text='&lt;%# Eval("Name") %&gt;'&gt;&lt;/asp:TextBox&gt;
                &lt;/EditItemTemplate&gt;
                &lt;ItemTemplate&gt;
                    &lt;asp:Label ID="txtName" runat="server" Text='&lt;%# Eval("Name") %&gt;'&gt;&lt;/asp:Label&gt;
                &lt;/ItemTemplate&gt;
            &lt;/asp:TemplateField&gt;
            &lt;asp:TemplateField AccessibleHeaderText="User_Name" HeaderText="User_Name"&gt;
                &lt;EditItemTemplate&gt;
                    &lt;asp:TextBox ID="TXT_USERNAME" runat="server" Text='&lt;%# Eval("User_Name") %&gt;'&gt;&lt;/asp:TextBox&gt;
                &lt;/EditItemTemplate&gt;
                &lt;ItemTemplate&gt;
                    &lt;asp:Label ID="txt_username" runat="server" Text='&lt;%# Eval("User_Name") %&gt;'&gt;&lt;/asp:Label&gt;
                &lt;/ItemTemplate&gt;
            &lt;/asp:TemplateField&gt;
            &lt;asp:TemplateField AccessibleHeaderText="Email" HeaderText="Email"&gt;
                &lt;EditItemTemplate&gt;
                    &lt;asp:TextBox ID="TXT_EMAIL" runat="server" Text='&lt;%# Eval("Email") %&gt;'&gt;&lt;/asp:TextBox&gt;
                &lt;/EditItemTemplate&gt;
                &lt;ItemTemplate&gt;
                    &lt;asp:Label ID="txt_email" runat="server" Text='&lt;%# Eval("Email") %&gt;'&gt;&lt;/asp:Label&gt;
                &lt;/ItemTemplate&gt;
            &lt;/asp:TemplateField&gt;
            &lt;asp:TemplateField AccessibleHeaderText="Password" HeaderText="Password"&gt;
                &lt;EditItemTemplate&gt;
                    &lt;asp:TextBox ID="TXT_PASSWORD" runat="server" Text='&lt;%# Eval("Password") %&gt;'&gt;&lt;/asp:TextBox&gt;
                &lt;/EditItemTemplate&gt;
                &lt;ItemTemplate&gt;
                    &lt;asp:Label ID="txt_password" runat="server" Text='&lt;%# Eval("Password") %&gt;'&gt;&lt;/asp:Label&gt;
                &lt;/ItemTemplate&gt;
            &lt;/asp:TemplateField&gt;
            &lt;asp:TemplateField AccessibleHeaderText="Date" HeaderText="Date"&gt;
                &lt;EditItemTemplate&gt;
                    &lt;asp:TextBox ID="TXT_DATE" runat="server" Text='&lt;%# Eval("Date") %&gt;'&gt;&lt;/asp:TextBox&gt;
                &lt;/EditItemTemplate&gt;
                &lt;ItemTemplate&gt;
                    &lt;asp:Label ID="txt_Date" runat="server" Text='&lt;%# Eval("Date") %&gt;'&gt;&lt;/asp:Label&gt;
                &lt;/ItemTemplate&gt;
            &lt;/asp:TemplateField&gt;
            &lt;asp:CommandField ShowEditButton="True" /&gt;
            &lt;asp:CommandField ShowDeleteButton="True" /&gt;
        &lt;/Columns&gt;
         &lt;HeaderStyle HorizontalAlign="Left" CssClass="header" BackColor="#7961da"
                                                            Font-Bold="True" ForeColor="White" /&gt;       
        &lt;RowStyle BackColor="#F7F6F3" ForeColor="#333333" /&gt;
    &lt;/asp:GridView&gt;

&lt;/div&gt;
&lt;/form&gt;
</code></pre>