Recursively set SharePoint MasterPages and CSS

Here is a quick sample of how to set master pages and CSS recursively and make sure that they are inherited from the parent site. This would be used within a SharePoint project’s FeatureEventReceiver class.

using System;
using System.Runtime.InteropServices;
using Microsoft.SharePoint;
namespace Acme.Intranet.Ui.Features.Feature1
{
    [Guid("0a7b9817-012b-4210-b4b9-a27913eb9598")]
    public class Feature1EventReceiver : SPFeatureReceiver
    {
        public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
            using (SPSite site = (SPSite)properties.Feature.Parent)
            {
                using (SPWeb web = site.RootWeb)
                {
                    string masterPageUrl = new Uri(web.Url + "/_catalogs/masterpage/Custom.master").AbsolutePath;
                    web.MasterUrl = masterPageUrl;
                    web.CustomMasterUrl = masterPageUrl;
                    web.Update();
                    foreach (SPWeb childWeb in web.Webs)
                    {
                        SetMasterPagesAndCss(site.Url, childWeb.ServerRelativeUrl, masterPageUrl, true);
                    }
                }
            }
        }

        public override void FeatureDeactivating(SPFeatureReceiverProperties properties)
        {
            using (SPSite site = (SPSite)properties.Feature.Parent)
            {
                using (SPWeb web = site.RootWeb)
                {
                    string masterPageUrl = new Uri(web.Url + "/_catalogs/masterpage/v4.master").AbsolutePath;
                    web.MasterUrl = masterPageUrl;
                    web.CustomMasterUrl = masterPageUrl;
                    web.Update();
                    foreach (SPWeb childWeb in web.Webs)
                    {
                        SetMasterPagesAndCss(site.Url, childWeb.ServerRelativeUrl, masterPageUrl, false);
                    }
                }
            }
        }

        public void SetMasterPagesAndCss(string siteUrl, string webUrl, string masterPageUrl, bool inheritsMasterAndCss)
        {
            string boolVal = "False";
            if (inheritsMasterAndCss)
            {
                boolVal = "True";
            }
            using (SPSite site = new SPSite(siteUrl))
            {
                using (SPWeb web = site.OpenWeb(webUrl))
                {
                    web.Navigation.UseShared = true;
                    web.MasterUrl = masterPageUrl;
                    web.AllProperties["__InheritsMasterUrl"] = boolVal;
                    web.CustomMasterUrl = masterPageUrl;
                    web.AllProperties["__InheritsCustomMasterUrl"] = boolVal;
                    web.AlternateCssUrl = web.ParentWeb.AlternateCssUrl;
                    web.AllProperties["__InheritsAlternateCssUrl"] = boolVal;
                    web.Update();
                    foreach (SPWeb childWeb in web.Webs)
                    {
                        SetMasterPagesAndCss(siteUrl, childWeb.ServerRelativeUrl, masterPageUrl, inheritsMasterAndCss);
                    }
                }
            }
        }
    }
}