Summary

This repository contains a minimal working example that demonstrates differences in syntax highlighting between sync and async Org Mode HTML export.

Instructions

In a terminal, run:

git clone git@github.com:dlukes/org-html-a-sync-export-syntax-highlighting.git
cd org-html-a-sync-export-syntax-highlighting
emacs -Q -l init.el test.org

Generate a sync HTML export and take a look at it (C-c C-e h o). Then, run an async export (C-c C-e C-a h h) and refresh the browser page. The syntax highlighting of the src block should differ:

sync export

colors are used in the syntax highlighting of the src block

async export

no colors, just bold / italics / possibly underline (not in the default theme, but I’ve seen it with other ones)

tl;dr (Too long; didn’t run)

For reference, exports as generated on my machine (Fedora 36) are provided in ./test-sync-ref.html and ./test-async-ref.html. Here’s the diff:

200,203c200,203
< <pre class="src src-python"><span style="color: #a020f0;">def</span> <span style="color: #0000ff;">foo</span>():
<     <span style="color: #8b2252;">"""Docstring"""</span>
<     <span style="color: #b22222;"># </span><span style="color: #b22222;">comment</span>
<     <span style="color: #a020f0;">pass</span>
---
> <pre class="src src-python"><span style="font-weight: bold;">def</span> <span style="font-weight: bold;">foo</span>():
>     <span style="font-style: italic;">"""Docstring"""</span>
>     <span style="font-weight: bold; font-style: italic;"># </span><span style="font-weight: bold; font-style: italic;">comment</span>
>     <span style="font-weight: bold;">pass</span>

I have seen the same results on macOS.

Additional information

I tried generating the exports directly as part of init.el using the following code at the end of the file:

(find-file (expand-file-name "test.org" straight-base-dir))
(org-html-export-to-html nil nil nil nil '(:html-extension "sync.html"))
(org-html-export-to-html t nil nil nil '(:html-extension "async.html"))

However, this generated identical exports, without colors in both cases.