Hi there,
Did you manually insert the link or did you use the Manage Styles window? In the latter case, it should update automatically and show the file you attached.
Which version of Visual Studio are you using? There have been changes between 2008 and later versions with regards to how sites open by default. Chapter 6 shows you how to move away from
http://localhost:12345/Site to
http://localhost:12345/ which may resolve this issue.
Cheers,
Imar