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Fix mermaid fullscreen overlay accessibility and add stable data-streamdown attribute #507

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Fix mermaid fullscreen overlay accessibility and add stable data-streamdown attribute #507

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1b5d457
fix(mermaid): update fullscreen button accessibility attributes
aradhyacp Apr 16, 2026
c791336
add changeset for fullscreen overlay accessibility and add stable sel…
aradhyacp Apr 16, 2026
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11 changes: 11 additions & 0 deletions .changeset/gold-feet-strive.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
---
"streamdown": patch
---

Fix mermaid fullscreen overlay accessibility and add stable selector

- Add `data-streamdown="mermaid-fullscreen"` to fullscreen overlay for stable CSS targeting
- Update fullscreen overlay semantics to match table fullscreen behavior
- Change `role` from `button` to `dialog`
- Add `aria-modal="true"` for correct screen reader modal behavior
- Improve accessibility consistency between mermaid and table fullscreen overlays
8 changes: 5 additions & 3 deletions packages/streamdown/lib/mermaid/fullscreen-button.tsx
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Expand Up @@ -93,19 +93,21 @@ export const MermaidFullscreenButton = ({

{isFullscreen
? createPortal(
// biome-ignore lint/a11y/useSemanticElements: "div is used as a backdrop overlay, not a button"
// biome-ignore lint/a11y/noNoninteractiveElementInteractions: "div is used as a backdrop overlay, not a button"
<div
aria-label={t.viewFullscreen}
aria-modal="true"
className={cn(
"fixed inset-0 z-50 flex items-center justify-center bg-background/95 backdrop-blur-sm"
)}
data-streamdown="mermaid-fullscreen"
onClick={handleToggle}
onKeyDown={(e) => {
if (e.key === "Escape") {
handleToggle();
}
}}
role="button"
tabIndex={0}
role="dialog"
>
<button
className={cn(
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