如何在透明背景的网站上创建一个可关闭的div？

<div id="popup-container">
  <div id="popup-content">
    <!-- 弹出框内容 -->
    <p>这是一个弹出框。</p>
    <button id="close-button">关闭</button>
  </div>
</div>

#popup-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5); /* 设置透明度为0.5 */
  display: flex;
  align-items: center;
  justify-content: center;
}

#popup-content {
  background-color: #fff;
  padding: 20px;
  border-radius: 5px;
}

// 获取弹出框容器和关闭按钮的元素
var container = document.getElementById("popup-container");
var closeButton = document.getElementById("close-button");

// 点击关闭按钮时隐藏弹出框
closeButton.addEventListener("click", function() {
  container.style.display = "none";
});