1 <!DOCTYPE html> 2 <html> 3 <head> 4 ????<title>Document</title> 5 ????<style type="text/css"> 6 ????????#a1 { 7 ????????????width: 100px; 8 ????????????height: 100px; 9 ????????????border: 1px solid blue;10 ????????????float: left;11 ????????????background-color: white;12 ????????}13 ????????#a2 {14 ????????????width: 200px;15 ????????????height: 200px;16 ????????????border: 1px solid blue;17 ????????????background-color: black;18 ????????????opacity: 0.6;19 ????????}20 ????????body {21 ????????????margin: 0;22 ????????????background-color: yellow;23 ????????}24 ????</style>25 </head>26 <body>27 ????<div id="a1"></div>28 ????<div id="a2"></div>29 </body>30 </html>测试结果截图：（在层次上，白色DIV处于透明黑色DIV下）
[未解决]在HTML+CSS中 设置opacity后float无效的问题
原文地址：https://www.cnblogs.com/byron18/p/9733969.html