Quarto default style (arrow-light) for code does not highlight dsBuiltIn and dsExtension, where arrow-dark does

Mở src/resources/pandoc/highlight-styles/arrow-light.theme và so sánh các mục BuiltIn và Extension của nó với arrow-dark.theme. Kiểm tra tài liệu Quarto mẫu trong issue, sau đó xác nhận rằng kiểu sáng cung cấp cho các phần tử đó một màu văn bản được xác định và nhất quán trên các ngôn ngữ được hiển thị.

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

The quarto default code style (arrow-light) does not highlight BuiltIn or Extension, instead just presenting those code elements in all languages as default text. This is in contrast to most other themes, including the arrow-dark style.

I would expect (based on syntax highlighting documentation) they would minimally be highlighted using the same colours as Function/Variable/Other styles.

Steps to reproduce

Sample quarto doc with different languages, using default highlighting. In typst none/auto/true/false are all builtins. In python abs/dict are builtins, [:upper:] is an Extension, in terraform the functions are highlighted as builtins. In light mode these are all presented as normal text, in dark they get highlighting

---
highlight-style: arrow
theme:
  light: flatly
  dark: darkly
format:
  html:
    embed-resources: true
---

```typst
#let config = (
  debug: none,
  width: auto,
  visible: true,
)

#let show-box(width: auto, border: none, fill: false) = {
  let has-border = border != none
  box(width: width, stroke: if has-border { border } else { none })
}
```


```python
import re
from statistics import mean

x = abs(-5)

y = dict(
    z = 5,
    b = 1
)

z = mean((1,2,3))

s = re.compile(r"\w{2}\d+[[:upper:]]*")
```

```terraform
locals {
  name    = trimprefix(upper("  hello-world  "), " ")
  offset  = abs(-42)
  items   = sort(["banana", "apple", "cherry"])
  joined  = join(", ", local.items)
  hash    = substr(sha256("my-id"), 0, 8)
}
```

test.html

Actual behavior

See attached HTML files

Expected behavior

I would expect the arrow-light.theme in src\resources\pandoc\highlight-styles to define text-color for BuiltIn and Extension, rather than leaving it null.

The arrow-dark.theme does colour BuiltIn and Extension - making them the same colours as Char and Variable respectively. This could be replicated in the light theme for consistency, or alternatively I would expect using the Function colours for both would improve the situation without being over coloured.

Your environment

• IDE: Positron 2026.03.0
• OS: Windows 11

Quarto check output

> quarto check
Quarto 1.8.27
[>] Checking environment information...
      Quarto cache location: C:\Users\Michael.Walshe\AppData\Local\quarto
[>] Checking versions of quarto binary dependencies...
      Pandoc version 3.6.3: OK
      Dart Sass version 1.87.0: OK
      Deno version 2.3.1: OK
      Typst version 0.13.0: OK
[>] Checking versions of quarto dependencies......OK
[>] Checking Quarto installation......OK
      Version: 1.8.27
      Path: C:\Program Files\Quarto\bin
      CodePage: 1252

[>] Checking tools....................OK
      TinyTeX: (external install)
      Chromium: (not installed)

[>] Checking LaTeX....................OK
      Using: TinyTex
      Path: C:\Users\Michael.Walshe\AppData\Roaming\TinyTeX\bin\windows\
      Version: 2024

[>] Checking Chrome Headless....................OK
      Using: Chrome found on system
      Path: C:\Program Files\Google\Chrome\Application\chrome.exe
      Source: Windows Registry

[>] Checking basic markdown render....OK

[>] Checking Python 3 installation....OK
      Version: 3.14.0
      Path: C:/Users/Michael.Walshe/AppData/Roaming/uv/python/cpython-3.14.0rc2-windows-x86_64-none/python.exe   
      Jupyter: (None)

      Jupyter is not available in this Python installation.
      Install with py -m pip install jupyter

[>] Checking R installation...........OK
      Version: 4.5.2
      Path: C:/PROGRA~1/R/R-45~1.2
      LibPaths:
        - C:/Users/Michael.Walshe/AppData/Local/R/win-library/4.5
        - C:/Program Files/R/R-4.5.2/library
      knitr: 1.51
      rmarkdown: 2.30

[>] Checking Knitr engine render......OK