anchor.diff:  
   (define-special-block import (url &rest media-queries)
     (list (list :attribute (format NIL "@import ~a~{ ~a~}"
  -                                 (selective-downcase url)
  -                                 (mapcar #'selective-downcase media-queries)))))
  +                                 (resolve url)
  +                                 (mapcar #'resolve media-queries)))))
   
   (define-special-block keyframes (identifier &rest body)
     (let ((inner (apply #'compile-sheet body)))
       (list (cons :block
  -                (cons (list (format NIL "@keyframes ~a" (selective-downcase identifier)))
  +                (cons (list (format NIL "@keyframes ~a" (resolve identifier)))
                         inner)))))
   
   (define-special-block media (selector &rest body)
  
positive.code:   (bind-vars bindings
      (apply #'compile-sheet body)))
  
  (defun generate (in &key (out (merge-pathnames (make-pathname :type "css") in)) (pretty NIL) (if-exists :supersede))
    (let ((eof (gensym "EOF")))
      (with-open-file (outstream out :direction :output :if-exists if-exists)
  
negative.code: 
  (define-special-block namespace (prefix/namespace &optional namespace)
    (list (list :attribute (format NIL "@namespace ~a~@[ ~a~]"
                                   (resolve prefix/namespace)
                                   (when namespace (resolve namespace))))))
  
  (define-special-block page (pseudo-class &rest body)
    (compile-block (format NIL "@page ~a"
                           (if (keywordp pseudo-class)
                               (format NIL ":~a" (string-downcase pseudo-class))
                               (resolve pseudo-class))) body))
  
  (define-special-block supports (selector &rest body)
    (let ((inner (apply #'compile-sheet body)))
  