I know that I can override a theme’s templates by creating my own copies in /layouts/ (and that works as expected for example with 404.html. But what would I do to override a theme’s partial? Providing my own copy of, for example, header.html in /layouts/partials/ does not seem to work.
Is it possible at all to override a theme’s partials that way?
Right. I should’ve taken a closer look at the theme – they put the partial in a subdirectory of partials. Replicating that setup in layouts does exactly what I hoped to achieve.