如何在overlay HTML - CSS中显示模式/面板

<div id="overlay" class="overlay"></div>
<div id="modal" class="modal">
    <div class="modal-content">
        <span class="close-button">&times;</span>
        <p>这是一个模态框！</p>
    </div>
</div>

.overlay {
    display: none; /* 默认隐藏 */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5); /* 半透明背景 */
    z-index: 1000; /* 确保在最上层 */
}

.modal {
    display: none; /* 默认隐藏 */
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: white;
    padding: 20px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.5);
    z-index: 1001; /* 确保在覆盖层之上 */
}

.close-button {
    cursor: pointer;
    float: right;
}

document.querySelector('.close-button').addEventListener('click', function() {
    document.getElementById('overlay').style.display = 'none';
    document.getElementById('modal').style.display = 'none';
});

// 假设有一个按钮来触发模态框
document.getElementById('openModalButton').addEventListener('click', function() {
    document.getElementById('overlay').style.display = 'block';
    document.getElementById('modal').style.display = 'block';
});