feat: 新增標籤外掛 timeline closed #644

fix: 自建頁面圖片沒有 blur 效果
improvement: 優化 404 頁面 UI
improvement: lazyload 默認佔位圖改為透明圖片
improvement: 優化 lazyload blur 出現特效
improvement: 優化 css

source/css/_layout/relatedposts.styl

@@ -16,11 +16,7 @@
       height: 200px
       background: $dark-black
       vertical-align: bottom
-
-      &:hover
-        .cover
-          opacity: .8
-          transform: scale(1.1)
+      @extend .postImgHover
 
       +maxWidth768()
         margin: 2px
@@ -30,13 +26,6 @@
       +maxWidth600()
         width: calc(100% - 4px)
 
-    .cover
-      width: 100%
-      height: 100%
-      opacity: .4
-      transition: all .6s
-      object-fit: cover
-
     .content
       position: absolute
       top: 50%