lib/attachment_to_html/template.html.erb
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title><%= title %></title>
<%= content_for(:head_suffix) %>
</head>
<body>
<%= content_for(:body_prefix) %>
<div id="<%= wrapper %>">
<div id="view-html-content">
<%= body %>
</div>
</div>
<%= content_for(:body_suffix) %>
</body>
</html>