Text in code blocks hardly visible in custom dark themes

[PeterCxy]

Description

Text in code blocks while using custom dark themes is hardly visible. It seems that the highlight.js theme is applied incorrectly (in the default dark theme, atom-one-dark is used for highlight.js, but it seems that it is not applied while using custom themes).

Steps to reproduce

• Apply a custom dark theme
• Notice that text in all code blocks look weird

Version information

• Platform: browser

For the web app:

• Browser: Firefox 90
• OS: Arch Linux
• Element Version: v1.7.33

Notes

Comparison between official dark theme and custom ones:

From top to bottom: default dark theme, Discord Dark Theme, Nord Dark.

After checking the generated theme-dark-custom.css (bundles/1bb29ac412a6c33a90c2/theme-dark-custom.css in my case), it seems that the hljs styles are simply not present there, but in theme-dark.css they are. Manually enabling theme-dark.css (by removing the disabled flag for the <link> element) while a custom theme is used seems to fix the code blocks, but this is probably the wrong way to do it.

[Oha-you]

I think the initial issue (as shown on the screenshots) has been fixed in v1.9.4 by matrix-org/matrix-react-sdk/pull/6384
However, another bug stays: hljs styles do not persist in code blocks when custom themes are used.

My observations:

• When you send a code block when using a custom theme (like Discord Dark), hljs styles are applied normally
• When you restart Element Desktop and you have a custom theme enabled by default (using "default_theme": "custom-Discord Dark" in config.json), code is not highlighted:
  
• If you switch to the default Dark theme and then back once, the code becomes highlighted:
  
• But if you repeat this step one more time, the text is grey again (no styles are applied, on restart too)

It looks like a hljs refresh event is not firing correctly for custom themes.

[SimonBrandner]

@Oha-you, could you please file a separate issue for that?

I am going to close this issue as it seems to be fixed!