让 DIV 元素半透明 - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>蜜蜂教程(mifengjc.com)</title>
  <style>
    #myDIV {
      position: absolute;
      width: 300px;
      height: 150px;
      background-color: lightblue;
      border: 1px solid black;
    }

    #DIV2 {
      position: relative;
      top: 130px;
      left: 30px;
      width: 300px;
      height: 150px;
      background-color: coral;
      border: 1px solid black;
    }
  </style>
</head>
<body>

  <p>点击“尝试一下”按钮，透过蓝色的 DIV 元素看到底下的珊瑚色的 DIV 元素。</p>
  <button onclick="myFunction()">尝试一下</button>
  <div id="DIV2">
    <h1>Voila!</h1>
  </div>
  <div id="myDIV">
  </div>
  <script>
    function myFunction() {
      document.getElementById("myDIV").style.opacity = "0.5";
    }
  </script>

</body>
</html>
        