fix: 修復 pagination UI 顯示異常的 bug

fix: 修復 footer_img 配置不生效的 bug
improvement: 優化 背景url 的判斷
feat: 背景圖片配置不再需要添加 url()

source/css/_global/index.styl

@@ -75,13 +75,12 @@ body
 input::placeholder
   color: var(--font-color)
 
-if $web-bg
+if hexo-config('background')
   #web_bg
     position: fixed
     z-index: -999
     width: 100%
     height: 100%
-    background: $web-bg
     background-attachment: local
     background-position: center
     background-size: cover

source/css/_layout/pagination.styl

@@ -38,6 +38,7 @@
   .next-post
     @extend .postImgHover
     position: relative
+    display: block
     overflow: hidden
     width: 50%
     height: 150px

source/css/var.styl

@@ -34,7 +34,6 @@ $font-size = hexo-config('font.global-font-size') ? convert(hexo-config('font.gl
 $code-font-size = hexo-config('font.code-font-size') ? convert(hexo-config('font.code-font-size')) : var(--global-font-size)
 $font-color = #1F2D3D
 $text-line-height = 2
-$web-bg = hexo-config('background') && unquote(hexo-config('background'))
 $index_top_img_height = hexo-config('index_top_img_height') ? convert(hexo-config('index_top_img_height')) : 100vh
 $index_site_info_top = hexo-config('index_site_info_top') ? convert(hexo-config('index_site_info_top')) : 43%
 // Global color & SVG