Combined CSS using handler is not working in firefox and chrome.

I am combining more than one CSS using a handler below.

<%@ WebHandler Language="C#" Class="HttpCombiner" %>

using System;

using System.Net;

using System.IO;

using System.IO.Compression;

using System.Text;

using System.Configuration;

using System.Web;

public class HttpCombiner : IHttpHandler {

    

    public void ProcessRequest(HttpContext context)

        {

        // Get the list of CSS files from QueryString.

        string files = context.Request.QueryString["fileName"];

        if (string.IsNullOrEmpty(files))

            {

                return; // If no file name is mentioned then don't proceed.

            }

        // Get the list of files specified in the querystring (joined by ',').

        string[] arrFileNames = files.Split(',');

        if ((arrFileNames != null) && (arrFileNames.Length > 0))

            {

            string filePath = string.Empty;

            // Read the content of each CSS file and write it in the response.

            for (int fileCount = 0; fileCount < arrFileNames.Length; fileCount++)

                {

                filePath = context.Server.MapPath(arrFileNames[fileCount]).Trim();

                if (File.Exists(filePath)) // Check if the file exists in the physical location or not.

                    {

                        context.Response.Write(File.ReadAllText(filePath));

                    }

                }

            //context.Response.ContentType = "text/css"; // Set the content type.

            }

        }

    public bool IsReusable

    {

        get

        {

            return true;

        }

    }

}

its working fine in IE 7.0 and above but not working in FireFox and Chrome.

when i include CSS Separately it working fine in all browsers.

any help or suggestion????