Apply Themes to an entire application

How Can you apply Themes to an entire application?
By specifying the theme in the web.config file.
Ex:
<configuration>
<system.web>
<pages theme="BlueMoon" />
</system.web>
</configuration>

How do you exclude an ASP.NET page from using Themes?
To remove themes from your page, use the EnableTheming attribute of the Page directive.

Page Level :
<%@ Page Language="C#" EnableTheming="false" Theme="Theme1" CodeFile="Default.aspx.cs" Inherits="_Default" %> 

Control Level:

<asp:TextBox ID="txtFirstName" EnableTheming="false" runat="server"></asp:TextBox>