Browser support
Oblyx targets evergreen Chrome, Firefox, Safari and Edge. No Internet Explorer, no polyfills. In practice that floor is higher than "whatever shipped this year" for a handful of components: they depend on specific, real platform features, and those features have their own support floors, listed below. This page states them plainly rather than claiming blanket support that doesn't hold.
Platform features Oblyx depends on
Grepped directly from the component source and stylesheets, not a general list of "modern CSS." Version numbers below were checked against MDN and caniuse.com; where a range or an approximate figure is given, it is marked as such.
| Feature | Used by | Chrome | Edge | Firefox | Safari |
|---|---|---|---|---|---|
Native <dialog> and showModal() | Dialog, Drawer | 37 | 79 | 98 | 15.4 |
Popover API (popover, showPopover()/hidePopover()) | Popover, Tooltip, Menu, Select | 114 | 114 | 125 | 17.0 |
CSS anchor positioning (anchor-name, position-anchor, position-area, position-try-fallbacks) | Popover, Tooltip, Menu, Select | 125 | 125 | 147 | 26.0 |
@starting-style | Dialog, Drawer, Popover, Tooltip | 117 | 117 | 129 | 17.5 |
transition-behavior: allow-discrete | Dialog, Drawer, Tooltip | 117 | 117 | 129 | 17.4 |
The one that matters: anchor positioning
Every other row in that table has been broadly available for a few years and is very unlikely to be the reason a real visitor sees something broken. CSS anchor positioning is different: it is the newest of the group by a wide margin, and it's what places a popover, tooltip, menu or select dropdown next to the element that opened it, with the browser handling viewport-edge collision on its own (no JavaScript measurement).
Chrome and Edge have had it since May 2024 (version 125). Firefox shipped it behind a flag first, then enabled it by default in Firefox 147, released January 2026. Safari shipped it in Safari 26, tied to macOS Tahoe, released fall 2025. That means a visitor on Firefox's extended support release, or on a Mac that can't or hasn't upgraded past an older macOS, is on a real, currently supported browser that still lacks this feature. This is not a hypothetical edge case the way "someone using IE11" would be.
What actually happens without it
Nothing crashes. anchor-name, position-anchor, position-area and position-try-fallbacks are all standard CSS: a browser that doesn't recognize them ignores them and keeps going, the same as any unsupported declaration. The Popover API itself (opening and closing the popup, light-dismiss, Escape-to-close) is a separate, older feature and keeps working. What's lost is specifically the positioning: the popup still opens, but it is no longer tied to its trigger's location on screen. Oblyx does not currently ship a JavaScript positioning fallback for this case; the CSS-only approach (packages/oblyx/src/base/anchored-layer.ts) is a deliberate choice documented in that file, made because the platform mechanism removes the need for per-component measurement code entirely on supporting browsers. This page states that tradeoff rather than hiding it: on an unsupported browser, expect the popup to open in an unpredictable position rather than next to its trigger, until Oblyx adds a fallback or the unsupported share of traffic becomes negligible.
Not supported
Internet Explorer, any version. No polyfills are shipped or planned; the CSS features above have no practical polyfill that preserves their zero-JavaScript behavior.