refactor: Modify the configuration item for body background image

_config.yml

@@ -164,9 +164,13 @@ body:
     repeat: false
   # Mask effect of the background image.
   mask:
-    enable: false
+    enable: true
     # Opacity of mask (value: 0 ~ 1).
-    opacity: 0.5
+    opacity:
+      # Opacity of the mask for the body background image by default.
+      default: 0.1
+      # Opacity of the mask for the body background image in night mode.
+      night_mode: 0.6
 
 # Footer of your site.
 footer:

source/css/_common/outline/macro.styl

@@ -21,7 +21,7 @@ if (hexo-config('body.bg_image.enable')) {
       &::before {
         bodyBgSet();
         z-index: $z-index-1;
-        background-color: alpha(#000, hexo-config('body.mask.opacity'));
+        background-color: alpha(#000, hexo-config('body.mask.opacity.default'));
       }
     }
 
@@ -36,6 +36,16 @@ if (hexo-config('body.bg_image.enable')) {
       }
     }
   }
+
+  if (hexo-config('body.mask.enable')) {
+    .nightmode {
+      body {
+        &::before {
+          background-color: alpha(#000, hexo-config('body.mask.opacity.night_mode'));
+        }
+      }
+    }
+  }
 }
 
 .container {