openproject/app/views/custom_styles/_inline_css_logo.erb

<%#-- copyright
OpenProject is an open source project management software.
Copyright (C) 2012-2020 the OpenProject GmbH

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License version 3.

OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
Copyright (C) 2006-2013 Jean-Philippe Lang
Copyright (C) 2010-2013 the ChiliProject Team

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

See docs/COPYRIGHT.rdoc for more details.

++#%>

<% cache(CustomStyle.current) do %>
  <style type="text/css">
    <% logo_url = asset_path("logo_openproject_white_big.png") %>
    <% if apply_custom_styles? %>
      <%
        if CustomStyle.current.logo.present?
          logo_url = custom_style_logo_path(digest: CustomStyle.current.digest, filename: CustomStyle.current.logo_identifier)
        elsif CustomStyle.current.theme_logo.present?
          logo_url = asset_path(CustomStyle.current.theme_logo)
        end
      %>
    <% end %>

    .op-logo--link {
      background-image: url(<%= logo_url %>);
    }
  </style>
<% end %>