css stylesheet dominance

According to the normal workflow, for example by using the touchpro theme as base, I create a subtheme and edit the touchpro_subtheme.info in this way:

; Load your sitewide stylesheets and scripts.
; --------------------------------------------------------------------------------


stylesheets[all][] = color/color_module.css
stylesheets[all][] = subtheme.css

; 

This to make sure that my subtheme.css is dominant over "all" other stylesheets. However, artica created a cached css file that is dominant over my subtheme, namely: /sites/default/files/arctica-cache-touchpro_subtheme.css?mjjdfy. Also according to artica, the color css file is still dominant over my subtheme.css.
This is really confusing when working with this theme and the artica module. Why? 1. Because I don't know how to clear that cached css file. 2. Because I edited the .info of my theme as to make the subtheme.css dominant over the color_module.css, but this is not reflected in the final cascading order.