Add visibility management

denote/static/css/denote.css

@@ -111,7 +111,7 @@ div#categories div.name img
     margin : 1em;
 }
 
-#main_panel .note .title a
+.note .title a
 {
     color: black;
     text-decoration: none;

denote/static/js/denote.js

@@ -96,6 +96,7 @@ function category_setup()
 	category = categories.childNodes[i];
 	if (category.nodeType != Node.ELEMENT_NODE) continue;
 	categoryId = category.getAttribute("category_id");
+	if (categoryId == null) continue;
 	hide = false;
 	for(a=0; a<hidden_categories.length;a++)
 	{