When you create one of the Web Forms Mobile Application presentation project types, the resulting Web application can closely emulate a native app running on the mobile device. In particular, the mobile Web application contains themes for iOS, Android™, and Windows 8.1 or higher operating systems (refer to Included Themes). The application can select the correct theme, dynamically, at runtime, enabling a single ePortal presentation application to provide a Web application which closely emulates a native app on each supported platform.

In ASP.Net, a theme is a collection of property settings that allow you to define the look of pages and controls, and then apply that look, consistently, across an entire Web application. Themes are made up of a set of elements: skins, cascading style sheets (CSS), images, and other resources. At a minimum, a theme will contain skins.

An ASP.Net StyleSheetTheme is a theme that is applied to a page early in the page life cycle. This means that settings on the page take precedence over settings in the StyleSheetTheme. This allows the application developer to set properties on individual controls to override the settings in the StyleSheetTheme.

For more information on themes, search for the following topics in the MSDN online documentation: