breaking changes: algolia 升級至 v4

feat:  本地搜索增加數據庫加載中和搜索中 loading 顯示
feat: 更改文章美化後,列表的顯示效果 closed #693 closed #686
improvement: UI 微調

source/css/_layout/aside.styl

@@ -258,7 +258,8 @@
 
     .toc-content
       clear: both
-      overflow-y: auto
+      overflow-y: scroll
+      overflow-y: overlay
       max-height: calc(100vh - 120px)
 
       +maxWidth900()
@@ -288,6 +289,7 @@
 
       .toc-link
         display: block
+        padding-right: 8px
         padding-left: 6px
         border-left: 3px solid transparent
         color: var(--toc-link-color)