How add css in .ashx.cs code behind in asp.net?

I want to add css class in .ashx page but .aspx Ui page show as string. How to add css in .ashx code behinde page.

I want (Cook) text show in red.

Issue:

try
{
for (int i = 0; i < dsSeaech.Tables[0].Rows.Count; i++)
{
var myString = new StringBuilder();
myString.Append("(Cook)");
lstRecipeName.Add(dsSeaech.Tables[0].Rows[i]["RecipeName"].ToString());
if (Convert.ToInt32(dsSeaech.Tables[0].Rows[i]["UserType"]) == AppConstant.chefuser)
{
lstChefName.Add(dsSeaech.Tables[0].Rows[i]["FullName"].ToString() + "(" + "Chef" + ")");
}
else if (Convert.ToInt32(dsSeaech.Tables[0].Rows[i]["UserType"]) == AppConstant.cook)
{
lstChefName.Add(dsSeaech.Tables[0].Rows[i]["FullName"].ToString() + myString);
}
}
JavaScriptSerializer js = new JavaScriptSerializer();
context.Response.Write(js.Serialize(lstRecipeName));
}
catch (Exception ex)
{
throw ex;
}