please explain your problem with more details, that we could clearly understand you.
This is not a XML Archive, this is a RSS Feed, and it should not have associated any style information. That's a default message displayed by the browser when it shows an XML file.
The RSS Feed is not designed to forum user viewing. It's a feed for search engines and feed readers. All works fine and there is no any issue here. For more information, please read this wiki article: https://en.wikipedia.org/wiki/RSS