The theme that is applied in the Microsoft Visual Studio HTML Designer is determined by the StyleSheetTheme property of the pages tag in the project’s web.config file.
For example:
<pages StyleSheetTheme="Android-light">
The value can be any one of the theme folder names in the App_Themes directory for the application. Refer to Included Themes. If you do not set a value, the BasicDevice stylesheets are applied by default, but no skin files are applied.
Note: When creating a new smartphone or tablet project, the StyleSheetTheme property is set to Android-light.
You can set the designer theme in either of the following ways:
Edit the web.config file and set the StyleSheetTheme property as shown above.
Use the Theme Management Dialog