title: How do I highlight a textbox border red when it is required?
body: <p>What property do I use on the required field validator control to make the textbox red if there is a validation error?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>&lt;asp:Label ID="lblFirstName" runat="server" AssociatedControlID="txtFirstName" Text="First Name:" CssClass="reg-labels" /&gt;
  &lt;br /&gt;
  &lt;asp:TextBox ID="txtFirstName" runat="server" CausesValidation="true" MaxLength="60" CssClass="standard_width"/&gt;
  &lt;asp:RequiredFieldValidator ControlToValidate="txtFirstName" runat="server" ID="valFirstName" ValidationGroup="grpRegistration" ErrorMessage="First Name is required." Text="*" /&gt;
  </code></pre>