Webrick:: Access to public folders (css, js etc)

Webrick serves "/" path, but I want to have direct access to css, js and other public folders.

if I use DocumentRoot, will handle all public paths too (like css/style.css), because it hadles root path:

server = WEBrick::HTTPServer.new(
 :DocumentRoot => Dir::pwd,
 :Port=>8080
 )
 

I need to mount_proc my root:

server.mount_proc('/') {|req,resp|  ...
 

How to give access to public folders?

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