{"html":"<!DOCTYPE html>\n<html>\n\n<head>\n    <meta charset=\"UTF-8\">\n    <style>\n       /* 填写样式 */\n       div::after {\n        content:\"\";\n            display:block;\n            width: 20px;\n            height: 20px;\n            background-color: rgb(255, 0, 0);\n        }\n    </style>\n</head>\n\n<body>\n  <div></div> \n    <script type=\"text/javascript\">\n        /* 填写JavaScript */\n        \n    </script>\n</body>\n\n</html>","css":"","js":""}

display和content一个都不能少