What for those who have a CSS template that's great, and you need to utilize it having a wordpress theme, but don't wish to edit all of the theme files to make use of the guidelines within the CSS template? It is possible to way to produce a CSS file that functions like a proxy between your new CSS template and old Wordpress theme?

Good question! I am afraid I believe there's no native way. There would need to be considered a syntax like

propertyname: inherit-from(.classname)     // Make believe example! Doesn't work

which does not appear in CSS proper.

It might most likely be achieved, though, utilizing a CSS pre-compiler like LeSS. LeSS's "Mixins" function appears like it could do exactly the thing you need. Using their top of the page:

.rounded_corners (@radius: 5px) 

#header 

where rounded_corners could be your original class definition, and #header the WordPress equivalent.