(defn remove-class 
 "Removes the specified classes from the selected element." 
 [& classes]
  #(let [classes (when-let [cl (attr-values % :class)] 
                   (reduce disj cl classes)) 
         attrs (:attrs %)
         attrs (if (empty? classes) 
                 (dissoc attrs :class) 
                 (assoc attrs :class (apply str (interpose \space classes))))]
     (assoc % :attrs attrs)))