当点击链接工作时，不能在两个颜色之间切换。

I have this link:

我有这个链接:

<div id='up_arrow_div'> 
<%= link_to "&uArr;".html_safe, video_votes_path( :video_id => video.id, :type => "up" ), :method => :post, :remote => true, :class => 'up_arrow' %>
</div>
<div id='up_arrow