It is possible to provide a custom html-header or -footer by providing the path to html files as env variables:
CUSTOM_HEADER_PATH
CUSTOM_FOOTER_PATH
If you need to serve an additional directory containing static files (your logo for example), you can do so by setting CUSTOM_STATIC_PATH. The folder will be served under /static.
If you want to serve an additional stylesheet, you can do so by setting CUSTOM_STYLESHEET_PATH.