In Visual Studion 2008 while working with code we use the “Go To Definition” or “F12” to go to the definition of a function from the function call, we can able to go to the CssClass from the aspx page by using “Go To Definition” or “F12”. It does not matter whether the CssClass is in Current Page or in an External style sheet.
The above code use a css class called “lblHeader”. If you want to go to the class definition of the css class then just put the cursor on the css class name and press F12 or Right click on the css class and select “Go To Definition” option from the popup menu. This will take you to the css class definition.
Hope this will help you to navigate easily between your aspx and css files.