js鼠标放在头像上显示窗口怎么在最上一层

<div id="avatar" class="avatar">
    <img src="path/to/avatar.jpg" alt="User Avatar">
</div>
<div id="tooltip" class="tooltip">
    这里是用户的信息
</div>

.avatar {
    position: relative;
    display: inline-block;
}

.tooltip {
    visibility: hidden;
    width: 120px;
    background-color: black;
    color: #fff;
    text-align: center;
    border-radius: 6px;
    padding: 5px 0;
    position: absolute;
    z-index: 1;
    bottom: 125%; /* Position the tooltip above the avatar */
    left: 50%;
    margin-left: -60px; /* Use half of the width (120/2 = 60) to center the tooltip */
    opacity: 0;
    transition: opacity 0.3s;
}

.avatar:hover .tooltip {
    visibility: visible;
    opacity: 1;
}

document.addEventListener('DOMContentLoaded', function() {
    const avatar = document.getElementById('avatar');
    const tooltip = document.getElementById('tooltip');

    avatar.addEventListener('mouseenter', function() {
        tooltip.style.visibility = 'visible';
        tooltip.style.opacity = '1';
    });

    avatar.addEventListener('mouseleave', function() {
        tooltip.style.visibility = 'hidden';
        tooltip.style.opacity = '0';
    });
});