anchor.diff:          font-size: 28px;
         }
         .site_header {
  -        left: 0;
  +        z-index: 100;
           top: 0;
  -        position: fixed;
  -        z-index: 1000;
  -        width: 100%;
  +        position: sticky;
           height: 3.5rem;
           border-bottom: 1px solid #cacaca;
  -        background: #FEFEFE;
  +        background: #fefefe;
           display: flex;
           align-items: center;
         }
  -      .site_title {
  +      .site_header__title {
           margin: 0 auto 0;
           font-size: 1.2rem;
           text-decoration: none;
           color: inherit;
         }
  -      .main {
  -        padding: 5rem 1.2rem 0;
  +      @media screen and (max-device-width: 480px) {
  +        main {
  +          width: 90%;
  +        }
         }
         .article__title {
  -        margin: 0;
  -        padding: 0;
  -        font-size: 1.5rem;
  +        margin-top: 0;
  +        padding-top: 0;
  +        font-size: 1.7rem;
           font-weight: 700;
  -        line-height: 2rem;
  +        line-height: 2.5rem;
           color: #333;
         }
         .article__published_on {
  
positive.code:         margin-top: 1.5rem;
          margin-bottom: 2rem;
          color: #545454;
        }
      </style>
    </head>
    <body>
      <header class='site_header'>
        <a href="/" class='site_title'><%= weblog.title %></a>
      </header>
      <section class='main'>
        <%= yield %>
      </section>
  
  
negative.code:     <script async custom-element="amp-youtube" src="https://cdn.ampproject.org/v0/amp-youtube-0.1.js"></script>
  
      <style amp-custom>
        @font-face {
           font-family: 'Noto Sans CJK JP';
           font-style: normal;
           font-weight: 400;
           src: local('Noto Sans CKJ JP Regular'),
             url(//fonts.gstatic.com/ea/notosansjapanese/v6/NotoSansJP-Regular.woff2) format('woff2'),
        }
        @font-face {
           font-family: 'Noto Sans CJK JP';
           font-style: normal;
           font-weight: 700;
           src: local('Noto Sans CKJ JP Bold')
            url(//fonts.gstatic.com/ea/notosansjapanese/v6/NotoSansJP-Bold.woff2) format('woff2'),
        }
        body {
          font-family: "Noto Sans", "Noto Sans CJK JP", sans-serif;
        }
        main {
          width: 80%;
          margin: 1rem auto;
        }
        a {
          overflow-wrap: break-word;
        }
        code {
          background-color: #f0f0f0;
          padding: 0.2em;
          border-radius: 4px;
          font-family: monospace, "Noto Sans", "Noto Sans CJK JP", sans-serif;
        }
        pre > code {
          display: block;
          border: none;
          line-height: 1.6em;
          padding: 0.5em;
          overflow-x: auto;
        }
        amp-social-share {
          margin-left: 5px;
  