modify: change base color for dark theme

Author: sota1235

browser/styles/index.styl

@@ -141,8 +141,8 @@ modal()
 
 // Dark theme
 $ui-dark-borderColor = lighten(#21252B, 20%)
-$ui-dark-backgroundColor = #333333
-$ui-dark-noteList-backgroundColor = #171717
+$ui-dark-backgroundColor = #1D1D1D
+$ui-dark-noteList-backgroundColor = #181818
 $ui-dark-noteDetail-backgroundColor = #0D0D0D
 $ui-dark-tag-backgroundColor = rgba(255, 255, 255, 0.3)
 $dark-background-color = lighten($ui-dark-backgroundColor, 10%)