app/views/redmine_lightbox/_view_layouts_base_html_head.html.erb
<% if attach_lightbox? %>
<%= stylesheet_link_tag('lightgallery.min.css', plugin: 'redmine_lightbox') %>
<%= stylesheet_link_tag('lightbox.css', plugin: 'redmine_lightbox') %>
<%= javascript_include_tag('lightgallery-all.min.js', plugin: 'redmine_lightbox') %>
<% end %>