从代码更改CSS类

我采用了AnthonyWJones的原始代码并对其进行了修改，以使其在任何情况下均能正常工作：

static class WebControlsExtensions    {        public static void AddCssClass(this WebControl control, string cssClass)        { List<string> classes = control.CssClass.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList(); classes.Add(cssClass); control.CssClass = classes.ToDelimitedString(" ");        }        public static void RemoveCssClass(this WebControl control, string cssClass)        { List<string> classes = control.CssClass.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList(); classes.Remove(cssClass); control.CssClass = classes.ToDelimitedString(" ");        }    }    static class StringExtensions    {        public static string ToDelimitedString(this IEnumerable<string> list, string delimiter)        { StringBuilder sb = new StringBuilder(); foreach (string item in list) {     if (sb.Length > 0)         sb.Append(delimiter);     sb.Append(item); } return sb.ToString();        }    }