清除浮动最后一个li元素为ie6和7

I have following html for menu

我有以下html菜单

<ul>
    <li id="btnHome"><a href="/go.html?url=#">Link One</a></li>
    <li id="btnAbout"><a href="/go.html?url=#">Link Two</a></li>
    <li id="btnContact"><a href="/go.html?url=#">Link Three</a></li>
    <li id="btnLinks"><a href="/go.html?url=#">Link Four</a></li>
</ul>
<