タイトルタグ付け忘れ

_layouts/default.html

@@ -36,6 +36,7 @@ body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:non
     <meta name="google-site-verification" content="{{ site.google_site_verification }}">
     {% endif %}
 
+    <title>{{ page.title }} | {{ site.title }}</title>
     <script async src="https://cdn.ampproject.org/v0.js"></script>
     <style amp-custom>{{ style }}</style>
     <style amp-boilerplate>{{ amp-boilerplate }}</style>