fix kramdown using curved quotes and replace them with straight quotation marks

app/assets/javascripts/pagedown/markdown.editor.js.erb

@@ -835,7 +835,7 @@
 
             var prevTime = new Date().getTime();
 
-            text = converter.makeHtml(text);
+            text = converter.makeHtml(text).replaceAll(/“|”/g, '"');
 
             // Calculate the processing time of the HTML creation.
             // It's used as the delay time in the event listener.

app/helpers/application_helper.rb

@@ -50,7 +50,7 @@ module ApplicationHelper
   end
 
   def render_markdown(markdown)
-    ActionController::Base.helpers.sanitize Kramdown::Document.new(markdown, input: 'GFM', hard_wrap: false).to_html.strip
+    ActionController::Base.helpers.sanitize Kramdown::Document.new(markdown, input: 'GFM', hard_wrap: false, smart_quotes: 'apos,apos,quot,quot').to_html.strip
   end
 
   def row(options = {}, &block)

app/models/submission.rb

@@ -314,7 +314,7 @@ class Submission < ApplicationRecord
     else
       # The render_markdown method from application_helper.rb is not available in model classes.
       ActionController::Base.helpers.sanitize(
-        Kramdown::Document.new(file.feedback_message).to_html,
+        Kramdown::Document.new(file.feedback_message, smart_quotes: 'apos,apos,quot,quot').to_html,
         tags: %w[strong],
         attributes: []
       )