To scroll or not to scroll
This property controls whether or not a background image scrolls with its containing block.
One of these keyword values:
|fixed||The background is in a fixed position and does not scroll, even if the text above it scrolls.|
|scroll||The background image scrolls, keeping in sync with the text placed above it.|
|local||The background image scrolls when the whole page scrolls, but remains fixed within the local element it is attached to.|