A host wrapper like .view{position:relative;z-index:1} creates a stacking context
that traps the modal's fixed overlay below a sibling sticky header, no matter its
z-index. Render the modal through a ModalPortal (createPortal to document.body) so
it escapes the host stacking context + overflow entirely; the portal root copies
the SDK theme tokens from the live surface (synchronously, no unstyled paint) and
carries dark defaults as a fallback. Adds react-dom peer dep. 67 tests green.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
maaz519
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