panel/app/views/layouts/application.html.haml

!!!
%html
  %head
    %meta{content: "text/html; charset=UTF-8", 'http-equiv': "Content-Type"}/
    %title Sutty
    = csrf_meta_tags
    = stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload'
    = javascript_include_tag 'application', 'data-turbolinks-track': 'reload'
    - if @site.try(:persisted?) && @site.try(:config).try(:dig, 'css')
      %link{rel: 'stylesheet', type: 'text/css', href: @site.get_url_from_site(@site.config.dig('css'))}
  - style = "background-image: url(#{@site.try(:cover) || image_url('background.jpg')})"
  %body{class: @has_cover ? 'background-cover' : '', style: @has_cover ? style : ''}
    #sutty.container-fluid
      = yield