Dear Rick,
the browser knows client video resolution thanks to media queries, but how to inform the server about client video resolution?
How a procedure may know about client video resolution and, for example, dimension a returning image rightly for client device?
Thank you very much again client video resolution

I suspect you need to pass back to the server the window or screen size of hte client browser as data in the request. This would require a small amount of javascript on the client.

There's no support for that in the browser as part of regular HTTP requests.

As Jim points out the only way you can do that is to capture the screen size in JavaScript and set it into a hidden variable and pass that back to the server.

+++ Rick ---

I solved with media queries, hiding and showing buttons, in order to launch a different procedure informing the server about client video resolution. I need only to know a range of video resolution: for example until to 600px, from 600px to 1024px, and so on.