app/views/invitation/index.html.erb
<div class = "invitation-title">Send Invitation Codes</div>
<div class = "message">
<% flash.each do |name, msg| %>
<%= content_tag :div, msg, class: "alert alert-info" %>
<% end %>
</div>
<div class = "box">
<%= form_tag("/invitation", method: "post") do %>
<div class = "notice_label">
<%= label_tag(:email, "Please enter your recipients' email addresses here, and make sure each email address is seperated by space or comma.")%>
</div>
<div class = "text_area">
<textarea name = "email" rows ="10" cols= "45"></textarea>
</div>
<div class = "submit_tag">
<%= submit_tag("Generate Invitation Code") %>
</div>
<% end %>
</div>