Browser support
Gelium UI is a server-rendered library: the baseline is modern HTML, and platform features are applied as progressive enhancements inside @supports so older browsers degrade to a usable native control. There is no single minimum version — the meaningful question is which platform APIs each feature relies on. This page consolidates the per-component Baseline notes.
Platform APIs in use
| API | Baseline status | Where it is used |
|---|---|---|
| Popover API | Baseline 2025 (newly available) | Menu — zero-JS popover positioning |
| CSS anchor positioning | Baseline 2026 | Menu positioning enhancement inside @supports |
| Invoker Commands | Baseline 2025 | Dialog/menu light-dismiss triggers |
<dialog> closedby |
not Baseline yet | Dialog light-dismiss when available; explicit close control otherwise |
The library never requires these APIs to function: each one is gated by @supports or by a documented fallback, so controls keep their native semantics and keyboard behavior on older browsers.
What always works
- Native HTML semantics:
input,button,dialog,select,menu— no component JavaScript to bundle. - Server round-trips with HTMX as a progressive enhancement; without JavaScript the same forms submit classically.
- WCAG AA contrast in light and dark, forced-colors borders, reduced-motion, and RTL — enforced by tests, not browser-dependent.
Per-component notes
See each component page's "Compatibility" section for the exact Baseline claims: Menu, Tooltip, Segmented buttons, Dialog, Navigation drawer.