CSS Property - Background Attachment
Value: scroll | fixed
Applies to: all elements
Percentage values: N/A
If a background image is specified, the CSS property "background-attachment" determines if the image is in a fixed position in relation to the screen or if it scrolls with the content.
CSS1 core: UAs may treat "fixed" as "scroll". However, it is recommended they interpret "fixed" correctly, at least on the "HTML" and "BODY" elements, since there is no way for an author to provide an image only for those browsers that support "fixed". (CSS1 conformance)