document brand-mode for typst

remove limitation fixed by
quarto-dev/quarto-cli#11811

Author: gordonwoodhull

docs/authoring/brand.qmd

@@ -200,14 +200,6 @@ logo:
 
 You can specify a local file path, relative to the location of `_brand.yml`, or a URL.
 
-::: {.callout-warning}
-
-## Limitation
-
-Logos specified as URLs are not currently supported in `format: typst`.
-
-::: 
-
 A single logo may not work well in all locations so **brand.yml** allows you to set three different logos: `small`, `medium` and `large`. For example:
 
 ``` {.yaml filename="_brand.yml"}
@@ -529,6 +521,14 @@ You can learn more about layering themes in [More About Quarto Themes](/docs/out
 
 ### Typst
 
+If the document has [both light and dark brands](#dark-brand), use `brand-mode: dark` to produce a dark-background PDF that matches the dark brand of your website.
+
+``` yaml
+format:
+  typst:
+    brand-mode: dark
+```
+
 In Typst documents, brand colors are set in a [dictionary](https://typst.app/docs/reference/foundations/dictionary/) called `brand-color`. 
 You can access them directory in raw Typst blocks using the syntax `brand-color.COLOR_NAME`.
 For example, you could make a rectangle filled with your `primary` brand color: