Version-sensitive. Every API name, SDK gate and browser-support claim below was verified on 2026-09-08 against primary sources. What against, and when, is in . If that date is old, re-verify before acting on a version number. Desktop Principles Desktop UX context. Loaded when desktop is detected (macOS, Windows, Linux desktop, web desktop). Concise rules here. Deep-dive in . --- Hover States Are Mandatory Hover is the primary affordance signal on desktop, the inverse of mobile. A pointer hovering over a target without immediate visual feedback feels broken: users rely on to confirm an element…