I am working with CloudFlare on fixing a problem where their product pages somewhat arbitrarily resets the mime type of the site css file. On my custom domain they provided a work around using a JS worker that resets the mime type for css in the http response header.
The works for production, which is based on the master branch (or any designated branch), that gets published and accessible via the custom domain.
For “development” (any branch that is not production), CloudFlare generates a new random dev url (subdomain) for each deployment. At this point, it is not easy to use a Worker to perform the workaround (this is also something they are changing where you will be able to use workers with Pages. (Workers otherwise work with content you are serving on CloudFlare through their other services.).
I am wondering if there is anything in Hugo that could tell the web server what header to use for a resource type (namely, css in this case). I note that the doc section on [[headers]] says it applies only to the hugo server (which of course is a memory based server totally under hugo’s control).