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/rightside.styl

@@ -18,7 +18,7 @@
     & > a
       display: block
       margin-bottom: 5px
-      width: w = 38px
+      width: w = 35px
       height: w
       border-radius: 5px
       background-color: var(--btn-bg)
@@ -30,11 +30,6 @@
       &:hover
         background-color: var(--btn-hover-color)
 
-      +maxWidth768()
-        width: w = 34px
-        height: w
-        line-height: w
-
   #mobile-toc-button
     display: none