convert.html.erb

<html>
    <head>
        <meta charset="utf-8">
        <link rel="stylesheet" href="https://cdn.rawgit.com/sindresorhus/github-markdown-css/gh-pages/github-markdown.css">
        <style>
            @media print {
                body {
                    zoom: 75%;
                }
                code, pre, tr {
                    background: none ! important;
                }
                table {
                    page-break-inside: avoid
                }
                td {
                    vertical-align: top;
                }
                .markdown-body pre {
                    margin: 0;
                }
            }
        </style>
    </head>
    <body class="markdown-body">
        <%
            http = Net::HTTP.new 'api.github.com', 443
            http.use_ssl = true
            response = http.post 'https://api.github.com/markdown/raw', STDIN.read, {'Content-Type'=>'text/x-markdown'}
            raise Exception.new "Unsuccessful response #{response.code}" unless response.code == '200'
        %>
        <%= response.body %>
    </body>
</html>