Thanks for the suggestions.
Both the live_view function in _web.ex and the options in the Live layouts Guide aim at using a different live.html though.
But I would like to use a different root.html.
The Live layouts Guide is actually contradicting. The paragraph on “the root layout” mentions
The root layout is typically declared on the router with put_root_layout and defined as “root.html.heex” in your MyAppWeb.LayoutView . It may also be given via the :layout option to the router’s live macro.
But the latter option is what is actually been removed in the latest version!