diff --git a/404.html b/404.html
deleted file mode 100644
index d19e5c3..0000000
--- a/404.html
+++ /dev/null
@@ -1,21 +0,0 @@
----
-layout: page
-title: "404: Page not found"
-permalink: /404.html
-
-redirect_from:
-  - /norobots/
-  - /assets/
-  - /posts/
-
-dynamic_title: true
----
-
-<div class="lead">
-  <p>Sorry, we've misplaced that URL or it's pointing to something that doesn't exist. </p>
-  <p>
-    <a href="{{ '/' | relative_url }}">Head back Home</a>
-    to try finding it again, or search for it on the
-    <a href="{{ 'archives' | relative_url }}">Archives page</a>.
-  </p>
-</div>
diff --git a/Gemfile b/Gemfile
index 78ccb94..e1f2ea3 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-gem "jekyll-theme-chirpy", "~> 3.3"
+gem "jekyll-theme-chirpy", "~> 4.0", ">= 4.0.0"
 
 group :jekyll_plugins do
   # If you have any plugins, put them here!
diff --git a/_config.yml b/_config.yml
index 82854a0..6608f19 100644
--- a/_config.yml
+++ b/_config.yml
@@ -50,15 +50,11 @@ google_site_verification: google_meta_tag_verification # change to your verifica
 # --------------------------
 
 google_analytics:
-  id: ''          # Fill with your Google Analytics ID
+  id: ''              # fill in your Google Analytics ID
+  # Google Analytics pageviews report settings
   pv:
-    # The Google Analytics pageviews switch.
-    # DO NOT enable it unless you know how to deploy the Google Analytics superProxy.
-    enabled: false
-    # the next options only valid when `google_analytics.pv` is enabled.
-    proxy_url: ''
-    proxy_endpoint: ''
-    cache: false  # pv data local cache, good for the users from GFW area.
+    proxy_endpoint:   # fill in the Google Analytics superProxy endpoint of Google App Engine
+    cache_path:       # the local PV cache data, friendly to visitors from GFW region
 
 # Prefer color scheme setting.
 #
@@ -105,10 +101,6 @@ kramdown:
       line_numbers: true
       start_line: 1
 
-# DO NOT change this unless you're a Pro user on Jekyll and Web development,
-# Or you think you're smart enough to change other relevant URLs within this template.
-permalink: /posts/:title/
-
 collections:
   tabs:
     output: true
@@ -124,6 +116,9 @@ defaults:
       layout: post
       comments: true    # Enable comments in posts.
       toc: true         # Display TOC column in posts.
+      # DO NOT modify the following parameter unless you are confident enough
+      # to update the code of all other post links in this project.
+      permalink: /posts/:title/
   -
     scope:
       path: _drafts
@@ -151,9 +146,6 @@ compress_html:
     envs: [development]
 
 exclude:
-  - vendor
-  - Gemfile
-  - Gemfile.lock
   - '*.gem'
   - '*.gemspec'
   - tools
@@ -162,8 +154,7 @@ exclude:
   - LICENSE
   - gulpfile.js
   - node_modules
-  - package.json
-  - package-lock.json
+  - '*.json'
 
 jekyll-archives:
   enabled: [categories, tags]
diff --git a/app.js b/app.js
deleted file mode 100644
index b821164..0000000
--- a/app.js
+++ /dev/null
@@ -1,8 +0,0 @@
----
-layout: compress
----
-
-/* Registering Service Worker */
-if('serviceWorker' in navigator) {
-  navigator.serviceWorker.register('{{ "/sw.js" | relative_url }}');
-};
diff --git a/feed.xml b/feed.xml
deleted file mode 100644
index aca721e..0000000
--- a/feed.xml
+++ /dev/null
@@ -1,60 +0,0 @@
----
-layout: compress
-# Atom Feed, reference: https://validator.w3.org/feed/docs/atom.html
----
-
-{% capture source %}
-<feed xmlns="http://www.w3.org/2005/Atom">
-  <id>{{ "/" | absolute_url }}</id>
-  <title>{{ site.title }}</title>
-  <subtitle>{{ site.description }}</subtitle>
-  <updated>{{ site.time | date_to_xmlschema }}</updated>
-  <author>
-    <name>{{ site.social.name }}</name>
-    <uri>{{ "/" | absolute_url }}</uri>
-  </author>
-  <link rel="self" type="application/atom+xml" href="{{ page.url | absolute_url }}"/>
-  <link rel="alternate" type="text/html" hreflang="{{ site.lang | default: 'en' }}"
-    href="{{ '/' | absolute_url }}"/>
-  <generator uri="https://jekyllrb.com/" version="{{ jekyll.version }}">Jekyll</generator>
-  <rights> © {{ 'now' | date: '%Y' }} {{ site.social.name }} </rights>
-  <icon>{{ site.baseurl }}/assets/img/favicons/favicon.ico</icon>
-  <logo>{{ site.baseurl }}/assets/img/favicons/favicon-96x96.png</logo>
-
-{% for post in site.posts limit: 5 %}
-  {% assign post_absolute_url = post.url | absolute_url %}
-  <entry>
-    <title>{{ post.title }}</title>
-    <link href="{{ post_absolute_url }}" rel="alternate" type="text/html" title="{{ post.title }}" />
-    <published>{{ post.date | date_to_xmlschema }}</published>
-  {% if post.last_modified_at %}
-    <updated>{{ post.last_modified_at | date_to_xmlschema }}</updated>
-  {% else %}
-    <updated>{{ post.date | date_to_xmlschema }}</updated>
-  {% endif %}
-    <id>{{ post_absolute_url }}</id>
-    <content src="{{ post_absolute_url }}" />
-    <author>
-      <name>{{ site.social.name }}</name>
-    </author>
-
-  {% if post.categories %}
-    {% for category in post.categories %}
-    <category term="{{ category }}" />
-    {% endfor %}
-  {% endif %}
-
-  {% if post.summary %}
-    <summary>{{ post.summary | strip }}</summary>
-  {% else %}
-    <summary>
-      {% include no-linenos.html content=post.content %}
-      {{ content  | strip_html | truncate: 400 }}
-    </summary>
-  {% endif %}
-
-  </entry>
-{% endfor %}
-</feed>
-{% endcapture %}
-{{ source | replace: '&', '&amp;' }}
diff --git a/robots.txt b/robots.txt
deleted file mode 100644
index 681b4c6..0000000
--- a/robots.txt
+++ /dev/null
@@ -1,10 +0,0 @@
----
-permalink: robots.txt
-# The robots rules
----
-
-User-agent: *
-
-Disallow: /norobots/
-
-Sitemap: {{ '/sitemap.xml' | absolute_url }}
diff --git a/sw.js b/sw.js
deleted file mode 100644
index 1b07241..0000000
--- a/sw.js
+++ /dev/null
@@ -1,60 +0,0 @@
----
-layout: compress
-# PWA service worker
----
-
-self.importScripts('{{ "/assets/js/data/cache-list.js" | relative_url }}');
-
-var cacheName = 'chirpy-{{ "now" | date: "%Y%m%d.%H%M" }}';
-
-function isExcluded(url) {
-  const regex = /(^http(s)?|^\/)/; /* the regex for CORS url or relative url */
-  for (const rule of exclude) {
-    if (!regex.test(url) ||
-      url.indexOf(rule) != -1) {
-      return true;
-    }
-  }
-  return false;
-}
-
-self.addEventListener('install', (e) => {
-  self.skipWaiting();
-  e.waitUntil(
-    caches.open(cacheName).then((cache) => {
-      return cache.addAll(include);
-    })
-  );
-});
-
-self.addEventListener('fetch', (e) => {
-  e.respondWith(
-    caches.match(e.request).then((r) => {
-      /* console.log(`[sw] method: ${e.request.method}, fetching: ${e.request.url}`); */
-      return r || fetch(e.request).then((response) => {
-        return caches.open(cacheName).then((cache) => {
-          if (!isExcluded(e.request.url)) {
-            if (e.request.method === "GET") {
-              /* console.log('[sw] Caching new resource: ' + e.request.url); */
-              cache.put(e.request, response.clone());
-            }
-          }
-          return response;
-        });
-
-      });
-    })
-  );
-});
-
-self.addEventListener('activate', (e) => {
-  e.waitUntil(
-    caches.keys().then((keyList) => {
-          return Promise.all(keyList.map((key) => {
-        if(key !== cacheName) {
-          return caches.delete(key);
-        }
-      }));
-    })
-  );
-});