Dark mode brokes tables with specified colors

[filip2cz]

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

Thunderbird for Android

App version

9.0

Where did you get the app from?

F-Droid

Android version

15

Device model

Pixel 6a (Bluejay)

Steps to reproduce

Create table with defined colors (I anonymized one where I found this issue and uploaded it below in eml format and renamed it so I can upload it). These black lines can be seen on big display, but I was not able to see them on mobile phone several times.

email.eml.txt

Expected behavior

If dark mode is enabled, colors should change so it is visible.

Actual behavior

Black colors are still black and people like me miss their english test because table looks completely different :D

Logs

No response

[faeryqueenrs]

I had a similar issue with a plain text email I received that discussed "the highlighted paragraph" but no highlighting was shown in dark mode. I can't share a picture because it was confidential information, but it was all one color like the table above.

[kewisch]

I could imagine we need to update the css for dark mode to use a luminance based approach and potentially enable algorithmic darkening: https://developer.android.com/develop/ui/views/layout/webapps/dark-theme

• legacy/ui/legacy/src/main/java/com/fsck/k9/view/MessageWebView.kt
• legacy/core/src/main/java/com/fsck/k9/message/html/DisplayHtml.kt

[kewisch]

I'm tentatively marking this as a good first issue, though I may be wrong. The investigation on what the issue is might well be good for someone to get started on though.