jquery二级导航菜单往上

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>jQuery 二级导航菜单</title>
    <style>
        .nav {
            list-style: none;
            padding: 0;
        }
        .nav li {
            display: inline-block;
            position: relative;
        }
        .sub-menu {
            display: none;
            position: absolute;
            top: 100%;
            left: 0;
            background-color: #fff;
            border: 1px solid #ccc;
            padding: 10px;
        }
    </style>
</head>
<body>
    <ul class="nav">
        <li>
            主菜单1
            <ul class="sub-menu">
                <li>子菜单1-1</li>
                <li>子菜单1-2</li>
            </ul>
        </li>
        <li>
            主菜单2
            <ul class="sub-menu">
                <li>子菜单2-1</li>
                <li>子菜单2-2</li>
            </ul>
        </li>
    </ul>

    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <script>
        $(document).ready(function() {
            $('.nav > li').hover(
                function() {
                    $(this).find('.sub-menu').slideDown(200);
                },
                function() {
                    $(this).find('.sub-menu').slideUp(200);
                }
            );
        });
    </script>
</body>
</html>

.sub-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: #fff;
    border: 1px solid #ccc;
    padding: 10px;
}

.nav > li {
    display: inline-block;
    position: relative;
}