It seems, that the attribute highlightjsdir is ignored for the preview and the file vscode_light+.min.css is searched in the VSCode extension folder .vscode\extensions\asciidoctor.asciidoctor-vscode-2 ...

TOML is becoming a widely supported config format, which includes markdown frontmatter for static site generators (eg: Hugo encourages TOML). It would be great if VS Code highlighted TOML frontmatter ...