anchor.diff:  
   (in-package :nyxt/dark-mode)
   
  +;;; When creating a style association you have two choices for
  +;;; matching, URL or predicate. By specifying a URL, the base domain
  +;;; is checked. If you specify a predicate, your predicate must accept
  +;;; a single argument (the URL), and return t or nil.
  +;;;
  +;;; You have three ways you can supply a style. You can supply it
  +;;; directly by specifying the style. You can supply it by specifying
  +;;; a style-file. You can supply it by specifying a style-url. If you
  +;;; specify a style-url, the resource at the URL will be downloaded
  +;;; and cached. To refresh the cached files, you must manually delete
  +;;; the old copies.
   (defstruct style-association
     (url)
     (predicate)
  
positive.code:                          :url "https://example.org"
                           :style (cl-css:css
                                   '((body
                                      :background-color "black"))))))
     (constructor
      (lambda (mode)
        (initialize mode)))))
  
negative.code:         when (and (style-association-predicate association)
                    (funcall (style-association-predicate association) url))
          return (style-association-style association)))
  