<ul class="menu">
    <li{luck:if $index} class="active"{/luck:if}><a href="{luck.site.url}">首页</a></li>
    {luck:nav }
    <li class="{luck:if $nav[child]}dropdown{/luck:if}{luck:if $on} active{/luck:if}">
        {luck:if $nav[child]}
        <div class="dropdown-box">
            {luck:nav parent_id=$nav[id]}
            <p><a href="{luck.nav.url}">{luck.nav.name}</a></p>
            {/luck:nav}
        </div>
        {/luck:if}
    </li>
    {/luck:nav}
</ul>