<link href="css/Rstyle.css" rel="stylesheet">
The more I look at this section, the less I like it. (Incidentally, is "meta charset" valid XHTML? I thought the shorter form was only for HTML 5.)
If you look it up
[w3.org], you'll find a long list of how file encoding for a stylesheet is determined. The default or fallback is: use whatever the HTML uses. (On w3's list the absolute default is UTF-8, but honestly I don't trust you-know-which browser to honor this.) If the stylesheet is referenced before the HTML's charset declaration, that would almost have to mean that the stylesheet's encoding matches the browser default
... and that, of course, is entirely up to the user. Note too that the server itself can set charsets. You said "microsoft" which to me implies IIS; there's a subforum for that.
I think you need to put your charset declaration back at the beginning of the html. It doesn't matter if it's before or after unrelated metas like "viewport", but there shouldn't be any other content before the charset is established. Once you're certain that you are sending the same information to all browsers, then
we can home in on the issue.
Do the stylesheets themselves contain any non-ASCII characters? Do they, in turn, reference any text content? (I'm having a hard time picturing how
, because normally a stylesheet wouldn't call on anything further except maybe fonts and images, but I may be overlooking something obvious.)
I tend to suspect that the whole stylesheet business is a red herring and the problem lies somewhere else. I seriously doubt it's an HTML issue, though. I would expect something with the database.