Just got puzzled and lost on this, i downloaded the jQueryUI Cupertino theme for a personal project. I do know how to use it when on single page, but just got stumped on how to convert the theme to a asp.net theme for use with masterpage, This is all i did but in vain,
Downloaded the Theme from the theme base
Created a App_Theme directory in the Project
Created a Cupertino theme folder inside the above directory
Copied all the css and images directory in the Cupertino theme downloaded
Set the Page.Theme to Cupertino , and Nothing happens :(
The Theme being set in MasterPage had been overridden in child page causing the confusion, removed the code that set's the theme in child page now works great.