Test CSS print-media output via Playwright `page.emulateMedia({ media: 'print' })` + `page.pdf()` - `@page` rule (size, margin, orphans, widows), `@page :first / :left / :right` pseudo-classes, `break-before/after/inside`, `@media print` selector activation, page-break suppression on headings. Use when an app exposes a Print button or a print stylesheet exists but is untested, and users report the printed or PDF copy breaking in the wrong places while the on-screen page looks fine.