app/views/layouts/mailer.html.erb
<html>
<head>
<title><%= message.subject %></title>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
</head>
<body style="font-family: Verdana, Helvetica, Arial, MS Trebuchet, sans-serif; font-size: 14px; width: 600px; background: #E5E5E5; padding: 15px">
<style>
h2 { font-size: 18px; }
h3 { font-size: 14px; }
a { color: black; }
</style>
<h1 style="background: #61970B; height: 75px; font-size: 24px; font-weight: normal; color: white; padding: 20px 0 0 30px;">Chouette</h1>
<div style="background: white; margin-bottom: 10px; padding: 15px; -moz-box-shadow: 3px 3px 4px #bbbbbb; -webkit-box-shadow: 3px 3px 4px #BBB; box-shadow: 3px 3px 4px #BBB; border-right: 1px solid #BBB; border-bottom: 1px solid #BBB;">
<%= yield %>
</div>
<div style="color: #333333; text-align:center; font-size: 10px;">
Envoyé par <%= link_to "Chouette", unauthenticated_root_url %>
</div>
</body>
</html>