When using a dark theme, giscus should use a dark theme as well.

[kdheepak]

Bug description

Right now giscus uses a light theme by default even when a dark theme is toggled.

Checklist

• Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
• Please format your issue so it is easier for us to read the bug report.
• Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
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• Please provide the output of quarto check so we know which version of quarto and its dependencies you're running.

[allenmanning]

Thanks for posting this.

I wanted to document a proposed approach here for review:

Setting Giscus Themes

Following the theme from the html format like

format:
  html:
    theme:
      light: lightly
      dark: darkly

We can now set Giscus themes to correspond

website:
  comments:
    giscus:
      theme:
        light: light
        dark: cobalt

So when the website is lightly Giscus will be light, and when darkly Giscus is cobalt.

Existing single string theme

The existing single string theme will still be supported

website:
  comments:
    giscus:
      theme: cobalt

It will expand out to be cobalt in both cases so it is equivalent to

website:
  comments:
    giscus:
      theme:
        light: cobalt
        dark: cobalt

Sensible Defaults

No Giscus theme

If none is specified like

website:
  comments:
    giscus:

this is equivalent to

website:
  comments:
    giscus:
        light: light
        dark: dark

Partial Giscus theme

If partially specified like

website:
  comments:
    giscus:
       dark: cobalt

We will fill in the default as

website:
  comments:
    giscus:
        light: light
        dark: cobalt

Note: The order of the Giscus themes has no special value. The single source of truth for default themes remains in the HTML format.