Active links' css is not working [on hold]

Active links' css is not working [on hold]

https://dl.dropboxusercontent.com/u/22558595/oDesk/JonathasHonorato_PluggedOffice/HTML/index.html
:active is not working in left sidebar
<div class="panel">
<div class="panel-heading">
<a class="accordion-toggle clients"
data-toggle="collapse"
data-parent="#accordion" href="#collapse2">
<span></span>Clients
</a>
</div>
<div id="collapse2" class="panel-collapse collapse">
<ul class="sub">
<li><a href="#"><i></i>Link</a></li>
<li><a href="#"><i></i>Link</a></li>
</ul> </div>
</div>