How to make dynamic css and theme
To make a Theme Changing Programatically
you need to set the Page.theme on preinit event of a Page.
Make a base class that override the preinint and your logical of changing theme.
PreInit
Use this event for the following:
Check the IsPostBack property to determine whether this is the first time the page is being processed.
Create or re-create dynamic controls.
Set a master page dynamically.
Set the Theme property dynamically.
Read or set profile property values.
Note:If
the request is a postback, the values of the controls have not yet been
restored from view state. If you set a control property at this stage,
its value might be overwritten in the next event
And then how to make dynamic css? just make a ashx which content type = text/css
finally how to Override the css from the App_Theme, which will generate pattern like app_them234234.css
you can add another link to the page by using page.header.add("<link string..");