Sec,ch,ua,mobile:,?0 ❲2026 Edition❳

: Serve expansive, multi-column designs rather than single-column mobile stacks.

: It follows the Structured Field Values format, using a question mark followed by a boolean: ?0 : Desktop (False). ?1 : Mobile (True). sec,ch,ua,mobile:,?0

: It is a "low-entropy" hint, meaning browsers like Chrome send it by default on every secure (HTTPS) request without the server needing to ask for it. : Serve expansive