Create, debug, and optimize Quarto `.qmd` PDF cheatsheets, especially dense A4 landscape multi-column sheets rendered with XeLaTeX. Use this skill whenever the user mentions Quarto cheatsheets, `.qmd` cram sheets, A4 landscape PDF notes, multi-column formula sheets, XeLaTeX/CJK cheatsheet layout, or wants to preserve/tune proven compact PDF layout details. It can also help with closely related R Markdown cheatsheet workflows when Quarto-specific guidance is not required.
