How to Add CSS Reference to .NET SyndicationFeed?

I have created a simple SyndicationFeed with many SyndicationItems. Each SyndicationItem has HtmlContent. The HtmlContent is a table. This displays OK, but now I need a minimum of styling/padding on the table. I believe I need to add a stylesheet reference like

<?xml-stylesheet type="text/css" href="http://you.com/rss.css" ?>

But I do not see how to do this with the .NET 4.5 SyndicationFeed or Atom10FeedFormatter classes.

Here is the (pseudo) code that is generated by a WCF service.

var feed = new feed(......);
var xqn = new XmlQualifiedName( "mysys" , "http://www.w3.org/2000/xmlns/" );
feed.AttributeExtensions.Add( xqn , myuri );
feed.ElementExtensions.Add( "creator" , "sys" , teaminfo );
feed.Authors.Add( new SyndicationPerson( emailaddr) );
feed.Categories.Add( new SyndicationCategory( mycategory ) );
feed.Description = new TextSyndicationContent( feedDesc );
feed.Copyright = SyndicationContent.CreatePlaintextContent(copyr);
feed.Language = "en-us";
feed.ImageUrl = new Uri( myuri + "/logo" );
var dbitems = GetListFromDb(key);
var syndItems = new List<synitem>();
foreach (var item in dbitems)
{
    var htmlContent =
        SyndicationContent.CreateHtmlContent( MakeHtmlFromStuff(item) );
    var itemUri = new Uri( myuri + itemuri );
    var synitem = new synitem( item.code , htmlContent , itemUri , item.key , DateTimeOffset.UtcNow );
    syndItems.Add( synitem);
}
feed.Items = syndItems;
return new Atom10FeedFormatter(feed);

Hopefully not missing something obvious. All ideas appreciated.

Thanks.

Solution

I believe I need to add a stylesheet reference like
<?xml-stylesheet type="text/css" href="http://you.com/rss.css" ?>
But I do not see how to do this with the .NET 4.5 SyndicationFeed or Atom10FeedFormatter classes.

Here is a complete code example how to do this:

using System;
using System.Collections.Generic;
using System.ServiceModel.Syndication;
using System.Xml;

namespace FeedProcessing
{
    class FeedProcessing
    {
        static void Main(string[] args)
        {
            FeedProcessing fp = new FeedProcessing();
            fp.CreateFeed();
        }
        public void CreateFeed()
        {
            SyndicationFeed feed = new SyndicationFeed("Feed Title", "Feed Description", new Uri("http://Feed/Alternate/Link"), "FeedID", DateTime.Now);
            // Add a custom attribute.
            XmlQualifiedName xqName = new XmlQualifiedName("CustomAttribute");
            feed.AttributeExtensions.Add(xqName, "Value");

            SyndicationPerson sp = new SyndicationPerson("jesper@contoso.com", "Jesper Aaberg", "http://Jesper/Aaberg");
            feed.Authors.Add(sp);

            SyndicationCategory category = new SyndicationCategory("FeedCategory", "CategoryScheme", "CategoryLabel");
            feed.Categories.Add(category);

            feed.Contributors.Add(new SyndicationPerson("lene@contoso.com", "Lene Aaling", "http://lene/aaling"));
            feed.Copyright = new TextSyndicationContent("Copyright 2007");
            feed.Description = new TextSyndicationContent("This is a sample feed");

            // Add a custom element.
            XmlDocument doc = new XmlDocument();
            XmlElement feedElement = doc.CreateElement("CustomElement");
            feedElement.InnerText = "Some text";
            feed.ElementExtensions.Add(feedElement);

            feed.Generator = "Sample Code";
            feed.Id = "FeedID";
            feed.ImageUrl = new Uri("http://server/image.jpg");

            TextSyndicationContent textContent = new TextSyndicationContent("Some text content");
            SyndicationItem item = new SyndicationItem("Item Title", textContent, new Uri("http://server/items"), "ItemID", DateTime.Now);

            List<SyndicationItem> items = new List<SyndicationItem>();
            items.Add(item);
            feed.Items = items;

            feed.Language = "en-us";
            feed.LastUpdatedTime = DateTime.Now;

            SyndicationLink link = new SyndicationLink(new Uri("http://server/link"), "alternate", "Link Title", "text/html", 1000);
            feed.Links.Add(link);

            XmlWriter atomWriter = XmlWriter.Create("atom.xml");
            atomWriter.WriteProcessingInstruction("xml-stylesheet", 
                                                  "type='text/css' href='http://you.com/rss.css'");
            Atom10FeedFormatter atomFormatter = new Atom10FeedFormatter(feed);
            atomFormatter.WriteTo(atomWriter);
            atomWriter.Close();

            XmlWriter rssWriter = XmlWriter.Create("rss.xml");
            rssWriter.WriteProcessingInstruction("xml-stylesheet",
                                                 "type='text/css' href='http://you.com/rss.css'");
            Rss20FeedFormatter rssFormatter = new Rss20FeedFormatter(feed);
            rssFormatter.WriteTo(rssWriter);
            rssWriter.Close();
        }
    }
}

When this program is executed, two files are created:

atom.xml:

<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type='text/css' href='http://you.com/rss.css'?>
<feed xml:lang="en-us" CustomAttribute="Value" xmlns="http://www.w3.org/2005/Atom">
    <title type="text">Feed Title</title>
    <subtitle type="text">This is a sample feed</subtitle>
    <id>FeedID</id>
    <rights type="text">Copyright 2007</rights>
    <updated>2012-12-28T19:50:18-08:00</updated>
    <category term="FeedCategory" label="CategoryLabel" scheme="CategoryScheme" />
    <logo>http://server/image.jpg</logo>
    <author>
        <name>Jesper Aaberg</name>
        <uri>http://Jesper/Aaberg</uri>
        <email>jesper@contoso.com</email>
    </author>
    <contributor>
        <name>Lene Aaling</name>
        <uri>http://lene/aaling</uri>
        <email>lene@contoso.com</email>
    </contributor>
    <generator>Sample Code</generator>
    <link rel="alternate" href="http://feed/Alternate/Link" />
    <link rel="alternate" type="text/html" title="Link Title" length="1000" href="http://server/link" />
    <CustomElement xmlns="">Some text</CustomElement>
    <entry>
        <id>ItemID</id>
        <title type="text">Item Title</title>
        <updated>2012-12-28T19:50:18-08:00</updated>
        <link rel="alternate" href="http://server/items" />
        <content type="text">Some text content</content>
    </entry>
</feed>

and rss.xml:

<?xml version="1.0" encoding="utf-8"?>
<?xml-stylesheet type='text/css' href='http://you.com/rss.css'?>
<rss xmlns:a10="http://www.w3.org/2005/Atom" version="2.0">
    <channel CustomAttribute="Value">
        <title>Feed Title</title>
        <link>http://feed/Alternate/Link</link>
        <description>This is a sample feed</description>
        <language>en-us</language>
        <copyright>Copyright 2007</copyright>
        <managingEditor>jesper@contoso.com</managingEditor>
        <lastBuildDate>Fri, 28 Dec 2012 19:50:18 -0800</lastBuildDate>
        <category domain="CategoryScheme">FeedCategory</category>
        <generator>Sample Code</generator>
        <a10:contributor>
            <a10:name>Lene Aaling</a10:name>
            <a10:uri>http://lene/aaling</a10:uri>
            <a10:email>lene@contoso.com</a10:email>
        </a10:contributor>
        <image>
            <url>http://server/image.jpg</url>
            <title>Feed Title</title>
            <link>http://feed/Alternate/Link</link>
        </image>
        <a10:id>FeedID</a10:id>
        <a10:link rel="alternate" type="text/html" title="Link Title" length="1000" href="http://server/link" />
        <CustomElement>Some text</CustomElement>
        <item>
            <guid isPermaLink="false">ItemID</guid>
            <link>http://server/items</link>
            <title>Item Title</title>
            <description>Some text content</description>
            <a10:updated>2012-12-28T19:50:18-08:00</a10:updated>
        </item>
    </channel>
</rss>

Explanation:

Whenever the XmlWriter instance is created, but before calling either:

atomFormatter.WriteTo(atomWriter);

or:

rssFormatter.WriteTo(rssWriter);

call the WriteProcessingInstruction() method on the respective XmlWriter instance, passing to it the two required parameters -- the name of the PI (in this case "xml-stylesheet") and the text of the PI (in this case "type='text/css' href='http://you.com/rss.css'").