console 命令行工具 X clear

console

<ul id="list">
	<li id="item0">
        <button>登录</button>
        <ul id="list2">
            <li id="item1">
                <button>我的</button>
            </li>
            <li id="item2">
                <button>登出</button>
            </li>
        </ul>
    </li>
</ul>

#list2 {
    display: none;
}

#list:hover #list2{
    display: block;
}