Print stylesheets & overriding a base theme style sheet Since adding a print style sheet and marking the screen stylesheets accordingly:

stylesheets[screen][] = css/example.css


rather than 

stylesheets[all][] = css/example.css 


The Genesis base themes are overriding the similarly named site styles in my sub theme. Specifically /sites/all/themes/genesis/genesis/css/layout.css is overriding my sub-theme layout.css file.

I've tried adding 'fake' calls to empty stylesheets (as per 'Overriding style sheets from modules and base themes'), with no success:

;----------// Modular Stylesheets

; Stop base overrides with fake file
; http://drupal.org/node/225125#comment-3028740
; http://drupal.org/node/263967
stylesheets[all][] = css/base.css
stylesheets[all][] = css/layout.css
stylesheets[all][] = css/blocks.css
stylesheets[all][] = css/comments.css
stylesheets[all][] = css/nodes.css
stylesheets[all][] = css/page.css
stylesheets[all][] = css/style.css

; block, comment, node, page and style CSS.
stylesheets[screen][] = css/blocks.css
stylesheets[screen][] = css/comments.css
stylesheets[screen][] = css/nodes.css
stylesheets[screen][] = css/page.css
stylesheets[screen][] = css/style.css
stylesheets[screen][] = css/layout.css
stylesheets[screen][] = css/forms.css
stylesheets[screen][] = css/rows.css

; Print css
stylesheets[print][] = css/print.css


I think the issue is that the later [screen] type is included as an extra stylesheet, rather than overriding the first [all]. But I can't see a way round it ....
You shouldn't be doing

stylesheets[][] = ...


Instead you should be doing

stylesheets[type][] = ...


type is the type of media to include the stylesheet for, like all, screen etc.