html

<div id="modalOverlay" class="modal-overlay" style="display:none;">
    <div class="modal-content">
        <div class="modal-title">
            <span>Titles</span>
        </div>
        <div class="close-button-top"> X </div>
        <div class="modal-text">
            <span>aaaaaaaaaaa </span>
            <a href="https://baidu.com/" target="_blank">
                百度
            </a>
        </div>
        <button class="close-button">OK</button>
    </div>
</div>

css

<style type="text/css">
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    display: flex;
    justify-content: center;
    align-items: center;
}

.modal-content {
    background-color: white;
    padding: 2px;
    border-radius: 5px;
    width: 450px;
    height: 220px;
    position: relative;
}
.modal-title{
    background : linear-gradient(to bottom, #87b6da , #70a8d2 );
    border-radius: 5px;
    font-size: 16px;
    color: #fff;
    padding: 12px 12px;
    font-weight: 600
}
.modal-text{
    height: 80px;
    padding: 20px 18px 15px 18px;
    border-bottom: 1px solid #70a8d2;
}
.close-button {
    position: absolute;
    bottom: 10px;
    right: 10px;
    font-size: 16px;
    cursor: pointer;
    background-color: #effef2;
    padding: 8px 18px;
    border-radius: 5px;
    color: #1d5987;
    font-weight: 600
}
.close-button-top {
    position: absolute;
    top: 10px;
    right: 10px;
    font-size: 18px;
    cursor: pointer;
    background-color: #f2f2f2;
    padding: 2px 6px;
    border-radius: 5px;
    font-weight: 600;
    color: #87b6da
}
.close-button:hover{
    background-color: #d0e5f5;
}
.close-button-top:hover{
    color: #70a8d2
}
</style>

js

// 模态窗口
    document.addEventListener('DOMContentLoaded', function() {
        var modal = document.getElementById('modalOverlay');
        var closeButton = document.querySelector('.close-button');
        var closeButtonTop = document.querySelector('.close-button-top');
        var openButton = document.getElementById('openModal'); // 假设有一个打开按钮的ID为openModal

        function openModal() {
            modal.style.display = 'flex';
        }
        function openImgButton() {
            modal.style.display = 'flex';
        }
        function closeModal() {
            modal.style.display = 'none';
        }
        closeButton.addEventListener('click', closeModal);
        closeButtonTop.addEventListener('click', closeModal);
        modal.addEventListener('click', function(e) {
            if (e.target === modal) {
                closeModal();
            }
        });
        if (openButton) {
            openButton.addEventListener('click', openModal);
        }
    });

效果图