diff --git a/_includes/head-custom-google-analytics.html b/_includes/head-custom-google-analytics.html
new file mode 100644
index 00000000..0055fb32
--- /dev/null
+++ b/_includes/head-custom-google-analytics.html
@@ -0,0 +1,20 @@
+  <!-- Google Analytics -->
+  {% if site.google_analytics %}
+  <script>
+      (function(i, s, o, g, r, a, m) {
+          i['GoogleAnalyticsObject'] = r;
+          i[r] = i[r] || function() {
+              (i[r].q = i[r].q || []).push(arguments)
+          }, i[r].l = 1 * new Date();
+          a = s.createElement(o),
+              m = s.getElementsByTagName(o)[0];
+          a.async = 1;
+          a.src = g;
+          m.parentNode.insertBefore(a, m)
+      })(window, document, 'script', '//www.google-analytics.com/analytics.js', 'ga');
+
+      ga('create', '{{ site.google_analytics }}', 'auto');
+      ga('send', 'pageview');
+
+  </script>
+  {% endif %}
diff --git a/_includes/head-custom.html b/_includes/head-custom.html
new file mode 100644
index 00000000..6cecfbc7
--- /dev/null
+++ b/_includes/head-custom.html
@@ -0,0 +1,2 @@
+<!-- start custom head snippets, customize with your own _includes/head-custom.html file -->
+{% include head-custom-google-analytics.html %}
diff --git a/_includes/head.html b/_includes/head.html
index afa3ac7e..8c70e401 100644
--- a/_includes/head.html
+++ b/_includes/head.html
@@ -1,11 +1,12 @@
 <head>
   <meta charset="UTF-8">
+  <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
 
-  <title>{{ site.title }}</title>
+  {% seo %}
 
   <!-- CSS -->
-  <link rel="stylesheet" href="{{ "/assets/css/main.css" | relative_url }}">
+  <link rel="stylesheet" href="{{ "/assets/css/main.css?v=" | append: site.github.build_revision | relative_url }}">
   <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Libre+Baskerville:400,400i,700">
   
   <!-- Font Awesome -->
@@ -14,25 +15,6 @@
   <!-- Favicon -->
   <link rel="icon" type="image/png" sizes="16x16" href="{{ "/assets/favicon.ico" | relative_url }}">
 
-  <!-- Google Analytics -->
-  {% if site.google_analytics %}
-  <script>
-      (function(i, s, o, g, r, a, m) {
-          i['GoogleAnalyticsObject'] = r;
-          i[r] = i[r] || function() {
-              (i[r].q = i[r].q || []).push(arguments)
-          }, i[r].l = 1 * new Date();
-          a = s.createElement(o),
-              m = s.getElementsByTagName(o)[0];
-          a.async = 1;
-          a.src = g;
-          m.parentNode.insertBefore(a, m)
-      })(window, document, 'script', '//www.google-analytics.com/analytics.js', 'ga');
-
-      ga('create', '{{ site.google_analytics }}', 'auto');
-      ga('send', 'pageview');
-
-  </script>
-  {% endif %}
+  {% include head-custom.html %}
 
 </head>
diff --git a/_includes/icons.html b/_includes/social.html
similarity index 93%
rename from _includes/icons.html
rename to _includes/social.html
index 7a9ad0f4..6fecd54e 100644
--- a/_includes/icons.html
+++ b/_includes/social.html
@@ -1,6 +1,6 @@
 {% if site.social.email %}
 <li>
-  <a href="mailto:{{ site.author.email }}" title="email">
+  <a href="mailto:{{ site.author.email | default: site.email }}" title="email">
     <span class="fa-stack fa-lg">
       <i class="fa fa-circle fa-stack-2x"></i>
       <i class="fa fa-envelope fa-stack-1x fa-inverse"></i>
@@ -64,9 +64,9 @@
 </li>
 {% endif %}
 
-{% if site.social.github %}
+{% if site.social.github or site.github_username %}
 <li>
-  <a href="https://github.com/{{ site.social.github }}" title="{{ site.social.default_txt }} GitHub">
+  <a href="https://github.com/{{ site.social.github | default: site.github_username }}" title="{{ site.social.default_txt }} GitHub">
     <span class="fa-stack fa-lg">
       <i class="fa fa-circle fa-stack-2x"></i>
       <i class="fab fa-github fa-stack-1x fa-inverse"></i>
@@ -196,9 +196,9 @@
 </li>
 {% endif %}
 
-{% if site.social.twitter %}
+{% if site.social.twitter or site.twitter_username %}
 <li>
-  <a href="https://twitter.com/{{ site.social.twitter }}" title="{{ site.social.default_txt }} Twitter" class="type">
+  <a href="https://twitter.com/{{ site.social.twitter | default: site.twitter_username }}" title="{{ site.social.default_txt }} Twitter" class="type">
     <span class="fa-stack fa-lg">
       <i class="fa fa-circle fa-stack-2x"></i>
       <i class="fab fa-twitter fa-stack-1x fa-inverse"></i>
diff --git a/_layouts/about.html b/_layouts/about.html
index 49b96121..6373c16e 100644
--- a/_layouts/about.html
+++ b/_layouts/about.html
@@ -1,25 +1,24 @@
 ---
-layout: base 
+layout: default
 ---
 
 <div class="about">
   <div class="profile">
-    <img class="selfie" alt="{{ site.author.name }}" src="{{ site.author.selfie }}" />
+    <img class="selfie" alt="{{ site.author.name | default: site.author }}" src="{{ site.author.selfie | default: site.github.owner_gravatar_url }}" />
     <div class="info">
-      <div class="title">{{ site.author.name }}</div>
-      <div class="description">{{ site.author.desc }}</div>
+      <div class="title">{{ site.author.name | default: site.author }}</div>
+      <div class="description">{{ site.author.desc | default: site.description | default: site.github.project_tagline }}</div>
     </div>
   </div>
 
-  <div class="content">
+  <section class="content">
     {{ content }}
-    </br>
-    <div class="social-layer">
-      <div class="social-icons">
-        <ul>
-          {% include icons.html %}
-        </ul>
-      </div>
+  </section>
+  <div class="social-layer">
+    <div class="social-icons">
+      <ul>
+        {% include social.html %}
+      </ul>
     </div>
   </div>
 </div>
diff --git a/_layouts/base.html b/_layouts/base.html
deleted file mode 100644
index f57228a0..00000000
--- a/_layouts/base.html
+++ /dev/null
@@ -1,29 +0,0 @@
-<!DOCTYPE html>
-<html lang="en">
-
-  {% include head.html %}
-
-  <body>
-    <nav class="nav">
-      <div class="nav-container">
-        <a href="{{ site.baseurl }}/">
-          <h2 class="nav-title">{{ site.title }}</h2>
-        </a>
-        <ul>
-          <li><a href="{{ '/' | prepend: site.baseurl }}">About</a></li>
-          <li><a href="{{ '/portfolio' | prepend: site.baseurl }}/">Portfolio</a></li>
-        </ul>
-    </div>
-  </nav>
-
-    <main>
-      {{ content }}
-    </main>
-
-    <footer>
-      <span>
-        &copy; <time datetime="{{ site.time }}">{{ site.time | date: '%Y' }}</time> {{ site.author.name }}. <a href="https://github.com/kssim/about-portfolio/">A.P</a> theme by kssim.
-      </span>
-    </footer>
-  </body>
-</html>
diff --git a/_layouts/default.html b/_layouts/default.html
new file mode 100644
index 00000000..1064a412
--- /dev/null
+++ b/_layouts/default.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<html lang="{{ site.lang | default: "en-US" }}">
+
+  {% include head.html %}
+
+  <body>
+
+    <header class="nav">
+      <div class="nav-container">
+        <a href="{{ site.baseurl }}/">
+          <h1 class="nav-title">{{ site.title | default: site.github.repository_name }}</h1>
+        </a>
+        <nav>
+          <ul>
+            <li><a href="{{ '/' | prepend: site.baseurl }}">About</a></li>
+            <li><a href="{{ '/portfolio' | prepend: site.baseurl }}">Portfolio</a></li>
+          </ul>
+        </nav>
+      </div>
+    </header>
+
+    <main>
+      {{ content }}
+    </main>
+
+    <footer>
+      <span>
+        &copy; <time datetime="{{ site.time }}">{{ site.time | date: '%Y' }}</time> {{ site.author.name | default: site.author }}. <a href="https://github.com/kssim/about-portfolio/">A.P</a> theme by kssim.
+      </span>
+    </footer>
+  </body>
+</html>
diff --git a/_layouts/portfolio.html b/_layouts/portfolio.html
index 711eff3a..2438a43c 100644
--- a/_layouts/portfolio.html
+++ b/_layouts/portfolio.html
@@ -1,5 +1,5 @@
 ---
-layout: base 
+layout: default
 ---
 
 <div class="portfolio">
diff --git a/_layouts/post.html b/_layouts/post.html
index 22124f27..52b1970d 100644
--- a/_layouts/post.html
+++ b/_layouts/post.html
@@ -1,14 +1,14 @@
 ---
-layout: base 
+layout: default
 ---
 
-<div class="post">
+<section class="post">
   <h2 class="post-title">{{ page.title }}</h2>
-  <div class="post-line"></div>
+  <hr class="post-line"/>
 
   {{ content }}
 
-</div>
+</section>
 
 <div class="pagination">
   {% if page.next.url %}
