I want to add some css rules to the this.Header.StyleSheet property. I need 
to add margin and some other css properties but the Style class doesn't 
support them. What is the best way or some other options to do this?
// Create a Style object for the body of the page.
Style style = new Style();
style.Width = val;
style.Margin-Left = 20px;  // this is what i would like to add
// Add the style to the header of the current page.
this.Header.StyleSheet.CreateStyleRule(style, null, "#container");
Many thanks
Andrew 
class MyStyle : Style
    {
        protected override void FillStyleAttributes(CssStyleCollection
attributes, IUrlResolutionService urlResolver)
        {
            base.FillStyleAttributes(attributes, urlResolver);
            attributes[HtmlTextWriterStyle.Margin] = "0 0 0 0";
            attributes[HtmlTextWriterStyle.Padding] = "0 0 0 0";
        }
    }
this.Page.Header.StyleSheet.CreateStyleRule(new MyStyle(), this.Page,
".myRule");
for Margin-Left rule simply add
attributes[HtmlTextWriterStyle.MarginLeft] = "20px";
Thanks for this. That's exactly what I needed.
Cheers
Andrew