css: factor out shared forum post / comment css.

app/views/comments/_index_by_comment.html.erb

@@ -1,5 +1,5 @@
 <div id="p-index-by-comment" class="comments-for-post">
-  <div class="list-of-comments">
+  <div class="list-of-comments list-of-messages">
     <% @comments.each do |comment| %>
       <% if CurrentUser.is_moderator? || (params[:search] && params[:search][:is_deleted] =~ /t/) || !comment.is_deleted? %>
         <%= content_tag(:div, { id: "post_#{comment.post.id}", class: ["post", *PostPresenter.preview_class(comment.post)].join(" ") }.merge(PostPresenter.data_attributes(comment.post))) do %>

app/views/comments/partials/index/_list.html.erb

@@ -11,7 +11,7 @@
     </div>
   <% end %>
 
-  <div class="list-of-comments">
+  <div class="list-of-comments list-of-messages">
     <% if comments.present? %>
       <%= render partial: "comments/partials/show/comment", collection: comments %>
     <% elsif post.last_commented_at.present? %>

app/views/comments/partials/show/_comment.html.erb

@@ -1,6 +1,6 @@
 <% if CurrentUser.is_moderator? || (params[:search] && params[:search][:is_deleted] =~ /t/) || !comment.is_deleted? %>
   <a name="comment-<%= comment.id %>"></a>
-  <article class="comment"
+  <article class="comment message"
            data-id="<%= comment.id %>"
            data-post-id="<%= comment.post_id %>"
            data-creator-id="<%= comment.creator_id %>"

app/views/comments/show.html.erb

@@ -1,7 +1,7 @@
 <div id="c-comments">
   <div id="a-show">
     <div class="comments-for-post">
-      <div class="list-of-comments">
+      <div class="list-of-comments list-of-messages">
         <%= content_tag(:div, { id: "post_#{@comment.post_id}", class: ["post", *PostPresenter.preview_class(@comment.post)].join(" ") }.merge(PostPresenter.data_attributes(@comment.post))) do %>
           <div class="preview">
             <% if @comment.post.visible? %>