DetailsView.aspx font size:
<html>
<title>Basic DetailsView Example</title>
<link rel="stylesheet" href="/shared/netdemos.css">

<script language="C#" runat="server">
   void Page_Load ( Object src, EventArgs e ) {
      // initialize selection
      if ( !IsPostBack ) customersGrid.SelectedIndex = 0;
   }
</script>
</head>

<body>
<!-- #include virtual="~/shared/top.inc -->
<div class="header"><h2>Basic DetailsView Example</h2></div>

<!-- #include virtual="~/shared/viewsrc_top.inc" -->
<hr size=1 width=92%>

<div align="center">
<form runat="server">

   <table width=92% align="center" cellpadding=5>
   <col width=50% align="center">
   <col width=50% align="center">
   <tr>
      <td>
      <asp:gridview id="customersGrid" runat="server"
         width=96% cellpadding=3
         datasourceid="customers"
         datakeynames="CustomerID"
         autogeneratecolumns=false>
         <columns>
            <asp:commandfield showselectbutton />
            <asp:boundfield datafield="ContactName" headertext="ContactName" />
            <asp:boundfield datafield="CompanyName" headertext="CompanyName" />
         </columns>
      </asp:gridview>
      </td>

      <td valign="top">
      <asp:detailsview id="customerDetails" runat="server"
         width=96% cellpadding=3
         datasourceid="details"
         headertext="Contact Details"
         datakeynames="CustomerID">

         <headerstyle font-bold 
            horizontalalign="center" />

      </asp:detailsview>
      </td>
   </tr>
   </table>

   <asp:sqldatasource id="details" runat="server"
      SelectCommand="SELECT * FROM Customers WHERE CustomerID = @CustomerID"
      connectionstring="<%$ ConnectionStrings:aspnet %>">

      <selectparameters>
         <asp:controlparameter controlid="customersGrid" name="CustomerID"
            propertyname="SelectedValue" />
      </selectparameters>
   </asp:sqldatasource>

   <asp:sqldatasource id="customers" runat="server"
      SelectCommand="SELECT CompanyName, ContactName, CustomerID FROM Customers"
      connectionstring="<%$ ConnectionStrings:aspnet %>" />

</form>
</div>

<hr size=1 width=92%>
<!-- #include virtual="~/shared/viewsrc.inc" -->

</body>
</html>