app/views/user_mailer/account_activation.html.erb
<div class="mail-wrapper">
<h1>Confirm your workdey account</h1>
<p>
Hi <%= "#{@user.firstname} #{@user.lastname}" %> <br class="line">
You recently registered on workdey, to confirm your account, please click on the link below
</p>
<%= link_to "Confirm my account", confirm_url(@user.confirm_token, email: @user.email), class: "btn", target: "_blank" %>
</div>