你好 玉振，
IE9新的安全机制要求web server送过来的 HTTP response header中的content-type 必需指明css文件的MIME-type为'text/css'，否则IE9不会把它作为css文件来处理。修正措施如下：
配置应用的web.xml文件中添加
css
text/css
For more information, you can refer here
另外如果你用iis 作为 web server，你可以配置一下mime type for css extension in iis manager。
希望对你有所帮助。
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