fix bug

app/helpers/application_helper.rb

@@ -335,15 +335,19 @@ module ApplicationHelper
   end
 
   def to_markdown(text)
-    nil if text.blank?
-    html_render_options = {
-        fenced_code_blocks: true,
-        tables: true,
-        autolink: true
+    return nil if text.blank?
+    options = {
+        :autolink => true,
+        :no_intra_emphasis => true,
+        :fenced_code_blocks => true,
+        :lax_html_blocks => true,
+        :strikethrough => true,
+        :superscript => true,
+        :tables => true
     }
 
-    markdown = Redcarpet::Markdown.new(html_render_options)
-    raw markdown.render(h(text)).html_safe
+    markdown = Redcarpet::Markdown.new(options)
+    markdown.render(h(text)).html_safe
   end
 
 end