Rework protective area border style

[Florimondable]

I am new to cyclosm and I like it a lot
I find natural parks border too heavy on the map. Dashed green is very similar to dashed blue (especially for colour blind people) so very often an invisible border looks like a path.
In my opinion cyclosm focus must be totally on paths/roads that can be cycled - border of national park is an accessory info that can be useful to a few people but misleading for a lot more people.

I suggest a lighter color for the border - or just a background of the area without (or with very faint) border

We have examples everywhere of problems with this heavy border

For instance:

1. near Milan we have a very large (with complex border) rural park (Parco Agricolo Sud) and cyclosm becomes a mess there
   

2. in the Netherlands for Eemmeer & Gooimeer Zuidoever
   where you can think there's a bridge where there's not
   

Originally posted by @rem-maps in #37 (comment)