The problem there is that a lot of websites will use minified stylesheets, or a stylesheet generated during deployment that is a combination of several smaller ones (particularly if they use SASS or LESS). That makes the resultant CSS file not particularly friendly to human readers, and somewhat difficult to pick apart.
Furthermore, a lot of designs are going to be dependent on a specific HTML structure, so even ripping the entire CSS file won't work when you apply it to your site.
You'd be better off using Chrome's Web Inspector, or Firebug, or Opera Dragonfly, and looking at how the site has achieved a particular effect/result. The Chrome WI Computed Style thing is pretty handy for this, and the Styles bit below that will list all the rules that apply to the selected element (with overridden ones crossed out).
I'm not so much wanting to apply their styles to my site, more a case of doing it the other way round and taking their design and layout and making changes to that.
I basically want to be able to take a page and make a template of some sort out of it.