The problem lies within CSS syntax:
/* Images should be linked as if the CSS file sits in the
same folder as the images. ie. no paths. */
with 
url(blossoms.jpg) in the rule while it should be
/001/blossoms.jpg
As the path appear nowhere and as the css file can be used
by any page from any folder, css files must be parsed
differently.  
Then the  only solution is to list the images with the full
path in the scan rules.