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<!DOCTYPE html> <html> <head> <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“试一试”按钮后，您可看穿蓝色 DIV 元素：</p> <button onclick="myFunction()">试一试</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>