Formsview 2010 formatting

Question

Within a formwview 2010 control, I have an html table where I want to format the header row. I would like to use CSS to format the header row. The CSS formatting is not picked up. Thus can you tell me what I need to do to the code below so that the CSS formatting  works for the code below?

The following is the code:

The following is from the CSS code:
FormviewheaderStyle
{
border-style: Solid; border-collapse: collapse; vertical-align: top; text-align: center;background-color: #5F809F;
  border-width: 1px 1px 1px 1px;color:White; font-family:Calibri; font-size:16; font-weight:bold;

}

The following is from the .aspx code:

<asp:FormView ID="FormView1" runat="server" DataSourceID="LinqDataSource1" AutoGenerateRows="False"
  HorizontalAlign="Center" DefaultMode="Edit" DataKeyNames="Attestation_id" BorderStyle="None"
  EnableModelValidation="True">
  <EditItemTemplate>
  <table  border="1" cellpadding="0" cellspacing="0">
  <tr class="FormviewheaderStyle">

<tr>
  <td>
  <asp:Label ID="Label2" runat="server" Text='Att ID'></asp:Label>
  </td>
  <td>
  <asp:Label ID="TextBoxAttid" runat="server" Text='<%# Eval("Att_id") %>'>
  </asp:Label>
  </td>
 
  </tr>
 
 
  <tr>
  <td>
  <asp:Label ID="Label10" runat="server" Text=' Submitted Late'></asp:Label>
  </td>
  <td>
  <asp:Label ID="lblSubmitLate" runat="server" Text='<%# Eval("Submitted_Late") %>' />
  </td>
 
  </tr>



  </table>
  </EditItemTemplate>
  </asp:FormView>