Fix cache-control

app/controllers/application_controller.rb

@@ -132,9 +132,11 @@ class ApplicationController < ActionController::Base
   # http://stackoverflow.com/questions/711418/how-to-prevent-browser-page-caching-in-rails
   def set_cache_buster
     if OpenProject::Configuration['disable_browser_cache']
-      response.headers['Cache-Control'] = 'no-cache, no-store, max-age=0, must-revalidate'
-      response.headers['Pragma'] = 'no-cache'
-      response.headers['Expires'] = 'Fri, 01 Jan 1990 00:00:00 GMT'
+      response.cache_control.merge!(
+        max_age: 0,
+        public: false,
+        must_revalidate: true
+      )
     end
   end
 

app/controllers/custom_styles_controller.rb

@@ -63,6 +63,7 @@ class CustomStylesController < ApplicationController
   def logo_download
     @custom_style = CustomStyle.current
     if @custom_style && @custom_style.logo
+      expires_in 1.years, public: true, must_revalidate: false
       send_file(@custom_style.logo_url)
     else
       head :not_found