Different Types of Themes
An ASP.NET page has two different properties that enable you to set a theme: the Theme property
and the StyleSheetTheme property. Both of these properties use the themes that you define in the
App_Themes folder. Both of these properties take their default value from the Web.config file as
you’ll see later. Although at first they seem very similar, it’s their runtime behavior that makes the
difference. The StyleSheetTheme is applied very early in the page’s life cycle, shortly after the page
instance has been created. This means that an individual page can override the settings from the
theme by applying inline attributes on the controls. So, for example, a theme with a skin file that
sets the BackColor of a button to blue can be overridden by the following control declaration in the
markup of the page: