HtmlAgilityPack remove elements by ID or class

namespace ZetaProducer.RuntimeBusinessLogic.Webbing.Printing
{
    using System;
    using System.Linq;
    using HtmlAgilityPack;

    internal static class PrintAgilityPackExtensions
    {
        public static void RemoveElementsByClass(this HtmlDocument doc, string className)
        {
            var nodes = doc.DocumentNode.SelectNodes(string.Format(@"//*[contains(@class,'{0}')]", className));
            if (nodes != null)
            {
                foreach (var node in nodes)
                {
                    if (node != null)
                    {
                        // Muss ganze Klasse haben.
                        var classes = node.Attributes[@"class"].Value;
                        if (containsFullWord(classes, className))
                        {
                            var parent = node.ParentNode;
                            if (parent != null)
                            {
                                parent.RemoveChild(node);
                            }
                        }
                    }
                }
            }
        }

        private static bool containsFullWord(string classes, string className)
        {
            if (string.IsNullOrWhiteSpace(classes) || string.IsNullOrWhiteSpace(className))
            {
                return false;
            }
            else
            {
                classes = classes.Trim();
                className = className.Trim();

                var raw = classes.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
                return raw.Any(s => string.Equals(s, className));
            }
        }

        public static void RemoveElementsByID(this HtmlDocument doc, string id)
        {
            var nodes = doc.DocumentNode.SelectNodes(string.Format(@"//*[@id='{0}']", id));
            if (nodes != null)
            {
                foreach (var node in nodes)
                {
                    var parent = node.ParentNode;
                    if (parent != null)
                    {
                        parent.RemoveChild(node);
                    }
                }
            }
        }
    }
}