1. Feature: the sidebar can auto scroll when the toc out of the screen

2. Fix: When the picture is loaded, the picture appears black frame

layout/includes/widget/card_categories.pug

@@ -1,3 +1,4 @@
+if site.categories.length
   .card_widget.card-categories
       .card-content
         .item_headline

layout/includes/widget/card_tags.pug

@@ -1,3 +1,4 @@
+if site.tags.length
   .card_widget.card-tags
     .card-content
       .item_headline

source/css/_global/index.styl

@@ -351,3 +351,8 @@ table
   position: fixed
   z-index: -1
   pointer-events: none
+
+
+// 去掉加載黑框
+img[src=""],img:not([src])
+  opacity: 0