XElement xmlTree = new XElement("Root",
    new XAttribute("Att1", "AttributeContent"),
    new XElement("Child",
        new XText("Some text"),
        new XElement("GrandChild", "element content")
    )
);
IEnumerable<XElement> de =
    from el in xmlTree.Descendants()
    select el;
foreach (XElement el in de)
    Console.WriteLine(el.Name);

<(?<Tag>([A-Za-z0-9])*?){1}(?<Attr>(|\s.*?))(|\/)>

Group "Tag":

HTML
BODY
DIV

Group "Attr":

http-equiv="Content-Language" content="en-us" 
http-equiv="Content-Type" content="text/html; charset=utf-8" 
http-equiv="X-UA-Compatible" content="IE=8" 

src="NewTabPageScripts.js" language="javascript" type="text/javascript"
type="text/css"

((?<Name>[A-Za-z0-9-_]*?)\s*=\s*(?<Value>"[^"=]*?"))

Group "Name":

http-equiv
content
http-equiv
http-equiv
src

Group "Value":

"Content-Language"
"en-us"
"Content-Type"
"X-UA-Compatible"
"NewTabPageScripts.js"
"javascript"
"text/javascript"