make mobile bar box shadow more subtle

Author: chrisvfritz

themes/vue/source/css/_header.styl

@@ -74,7 +74,7 @@ body.docs
     background-color #fff
     z-index 9
     display none
-    box-shadow 0 0 4px rgba(0,0,0,.25)
+    box-shadow 0 0 2px rgba(0,0,0,.25)
     .menu-button
         position absolute
         width 24px