To scroll or not to scroll
background-attachment
This property controls whether or not a background image scrolls with its containing block.
Property values
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. |