Template stylesheets

I am using the GoldenTemplate for my app and would like to hide the lm_header as I dont have usecases for neither maximizing or removing the “Content” tab or maximize the Sidebar.

The following raw_css works, but I would like to use the panel 1.x stylesheets to apply an encapsulated css, but I dont see an entrypoint to inject it for the template?

.lm_header { /* Hide the tabs header of the GoldenLayout */
    display: none;