The body.theme-dark catch-all from #4392 painted every section iframe's
body with the opaque theme bg in dark mode, occluding the host
background texture and poisoning foliate's docBackground capture (so
paginated segments and scrolled view backgrounds resolved opaque too).
Force transparent instead: the dark page fill already comes from the
paginator container / reader grid cell, and book-forced light page
backgrounds stay neutralized since the theme-dark fill shows through.
Unconditional rather than texture-gated because docBackground is
captured once per section load and a gated rule would go stale on live
texture toggling.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Huang Xin
852d0ae3e9