css去掉点击连接时所产生的虚线边框技巧兼容符

<ul class="about_nav">
<li class="nav1"><a href="about.html" class="fontnav ">狼蚁SEO</a></li>
<li class="nav2"><a href="about_webintro.html" class="fontnav">狼蚁SEO</a></li>
<li class="nav3"><a href="about_operation.html" class="fontnav">狼蚁SEO</a></li>
<li class="nav4"><a href="about_system.html" class="fontnav">狼蚁SEO</a></li>
<li class="nav5"><a href="about_contantus.html" class="fontnav">狼蚁SEO</a></li>
</ul>

a.fontnav { text-align:left;color:#555; text-decoration:none; outline:none}