How to send 'content disposition' using ESP8266webserver

As in the topic, i am trying to persuade my browser to open a file-save dialog for the content that i am sending, and for that i think i need to add a 'header' to the stream. Content-Disposition: attachment; filename="cool.html"For instance. The Asyncwebserver does have something builtin, but the normal espwebserver doesn't as far as i can tell. Does anybody know a way around it ?

server.sendHeader(name, value)
before server.send

yeah i tried that, but that didn't work as i hoped. On 2nd attempt i managed though, now let's see if i can make it create the proper file suggestion.