4个都没变化，且opacity=0属性没用

试了下代码能出<!DOCTYPE html> <html> <head> <title></title> <meta charset="UTF-8"> <style> .st-container { height: 100px; width: 200px; position: relative; } .st-container input:checked + a, .st-container input:checked:hover + a { background-color: #821134; /*设置被选中了颜色恒定不变*/ } .st-container input:checked + a:after { content: ""; width: 0; height: 0; overflow: hidden; border: 20px solid transparent; border-bottom-color: #821134; position: absolute; bottom: 100%; left: 50%; margin-left: -20px; /*使三角形居中的方法*/ /*温习下:after的用法*/ } .st-container input:hover + a { background: #AD244F; /*鼠标滑过的背景颜色发生变化*/ } </style> </head> <body> <div class="st-container"> <input type="checkbox"/> <a>sdfasdfsdf</a> </div> <div class="st-container"> <input type="checkbox"/> <a>sdfasdfsdf</a> </div> <div class="st-container"> <input type="checkbox"/> <a>sdfasdfsdf</a> </div> <div class="st-container"> <input type="checkbox"/> <a>sdfasdfsdf</a> </div> </body> </html>

4个都没变化，且opacity=0属性没用

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