Add zoom and dpi values to correct the pdf display when environment is not development.

app/controllers/dashboard/poster_controller.rb

@@ -7,6 +7,8 @@ class Dashboard::PosterController < Dashboard::BaseController
       format.pdf do
         render pdf: 'poster',
                page_size: 'A4',
+               dpi: 300,
+               zoom: 0.32,
                show_as_html: Rails.env.test? || params.key?('debug'),
                margin:  { top: 0 }
       end