Reusing jQuery UI Themeroller Overlay

Trying to conserve css-loading bandwidth. I'm trying to reuse the overlay from jQuery UI for just a small section of the page - say, within 开发者_如何学Pythona certain div. Can't seem to get the overlay to cover anything but a (semitransparent) blackout of the entire page. Integration CSS help, please!

Seems your question was answered here How can I just open an Overlay (like dialog without title bar) in jQuery UI