Adding a category class to your octopress blog so you can attached an icon/color to the cat. two methods

_category_style.scss

// Or use this method...
//
// E[foo$="bar"]	
// an E element whose "foo" attribute value ends exactly with the string "bar"
//
// http://www.w3.org/TR/css3-selectors/#attribute-selectors

a.category[href$="css/"] { 
  padding-left: 20px;
  background: url('your-icon.png') left center no-repeat;
}


// this works really well because you won't need the '/' at the end of your string.
a.category[href*="css"] { 
  padding-left: 20px;
  background: url('your-icon.png') left center no-repeat;
}

category_generator.rb

# or you could just add a class
# line 146 of category_generator.rb

--- "<a class='category' href='/#{dir}/#{item.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-').downcase}/'>#{item}</a>"
+++  "<a class='category #{item}' href='/#{dir}/#{item.gsub(/_|\P{Word}/, '-').gsub(/-{2,}/, '-').downcase}/'>#{item}</a>"