c2bbb6119a
On a multi-column spread a coloured page's background bled into the outer margin gutter (the --_outer-min track) while an adjacent transparent/image page did not, shifting cover/title spreads off-centre. Bump foliate-js to clamp each background segment to its column instead of stretching into the gutter, keeping the symmetric margins intact. Update the computeBackgroundSegments regression tests. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>