ref: master
public/designs/themes/profile-base/site_title.html.erb
<% if File.exists?(File.join(Rails.root, 'public', "/designs/themes/#{environment.theme}/images/thin-logo.png")) %>
<%= link_to(image_tag("/designs/themes/#{environment.theme}/images/thin-logo.png"), top_url) %>
<% else %>
<%= link_to(image_tag("/designs/themes/noosfero/images/thin-logo.png"), top_url) %>
<% end %>