Tend towards proportional fonts in :help.

common/content/dactyl.js

@@ -523,6 +523,16 @@ var Dactyl = Module("dactyl", XPCOM(Ci.nsISupportsWeakReference, ModuleBase), {
         return null;
     },
 
+    /**
+     * @private
+     */
+    initDocument: function initDocument(doc) {
+        if (doc.documentURIObject.scheme === "dactyl") {
+            dactyl.initHelp();
+            config.styleHelp();
+        }
+    },
+
     /**
      * @private
      * Initialize the help system.