epub and Bluefire Reader (iOS / iPadOS) dark mode

[pronoiac]

Summary

I made an epub, and the text doesn't change from black when in dark mode in Bluefire Reader on my iPad.

• HonKit version: 3.7.1
• Calibre / ebook-convert version: 5.40.0

Step to reproduce

1. Generate an epub.
2. Open it in Bluefire Reader.
3. Switch from light theme to dark theme, while watching some text.

• Link to code example: My book.json code is basic, with only root, title, and author. While I haven't committed it yet, as this is exploratory, let me know if it would be useful.

Expected results

In dark mode / dark theme, the text is lighter.
These are the results whether generated with pandoc, or viewed in Apple Books.

Actual results

In dark mode / dark theme, the text is black.
I verified it wasn't just my setup by looking at the most recent Byte of Python epub, which was a top result to googling "honkit epub", and confirming the issue is there.

[azu]

I'm not very familiar with dark mode in epub, but we need to improve this.

Probably, we need to modify epub.less to fix this issue.
https://github.com/honkit/honkit/tree/master/packages/%40honkit/theme-default/src/less

• html - Any way to detect if dark theme is active in iBooks from within EPUB? - Stack Overflow
• Apple Books Asset Guide 5.2.12
• Pure CSS ePub theme detection (White / Sepia / Night) in iBooks (Mac OS and iOS included)

[pronoiac]

Note, I've been in touch with Bluefire support, including sending a link to this issue.

For quicker iterating:

• I can reproduce the issue in calibre's ebook-viewer.
• A quick and dirty way to repack a folder into an epub: zip -rX ../alpha-testing.epub mimetype META-INF/ OEBPS/ *

Theory:
The ebook's font color settings override the app's.
(In comparison, I looked at a pandoc epub; its stylesheet1.css was empty.)

Workaround:
Commenting out lines with colors in stylesheet.css - color or background and #[0-9a-f]+ - seems to fix the issue.
Hitting .section did the most, fixing the main text, but I kept hitting more cases, so I ended up commenting them all out.
(This didn't include border, yet, though maybe it should.)