What are the 3 levels at which a theme can be applied for a web application in Asp.Net

What are the 3 levels at which a theme can be applied for a web application?

1. At the page level 

    Use the Theme or StyleSheetTheme attribute of the @ Page directive.

2. At the application level 

   Can be applied to all pages in an application by setting the <pages> element in the application configuration file.

3. At the web server level 

    Define the <pages> element in machine.config file. This will apply the theme to all the web applications on that web server.