内容长度提醒

app/views/admin/messages.html.erb

@@ -8,6 +8,7 @@
       <div class="field">
         <%= f.kindeditor :content, :edit_id => 'system_message', :width => '87%', :resizeType => '0', :no_label => true %>
       </div>
+      <div class="admin_message_warn">（消息内容不超过255个字符！）</div>
       <div>
         <p id="content_notice_span" class="ml55"></p>
       </div>

public/stylesheets/application.css

@@ -2808,3 +2808,5 @@ img.school_avatar {
     height: 100px;
     max-width: none;
 }
+
+.admin_message_warn{font-size: 12px;color: red;}