string.Format 中不能包含{}字符串

string scss = @"<style type=""text/css"">
body{
    margin-left: {0}px;
    margin-top: {1}px;
}
</style>";
            scss = string.Format(scss, marginleft, margintop);

        public void AddcssBody(int marginleft=2,int margintop=2)
        {
            string scss = @"<style type=""text/css"">
body{2}
    margin-left: {0}px;
    margin-top: {1}px;
{3}
</style>";
            scss = string.Format(scss, marginleft, margintop, "{", "}");
            Headary.Add(scss);
        }