https://drafts.csswg.org/css-pseudo-4/#highlight-styling

The following properties apply to the highlight pseudo-elements:

• […]
• text-decoration and its associated properties
• text-shadow
• […]

The current spec text could be interpreted as only allowing ‘text-decoration’ and ‘text-decoration-*’ and ‘text-shadow’, which would include line decorations and text shadows, but not emphasis marks or ‘text-underline-position’ or ‘text-underline-offset’. Should we somehow allow those properties more explicitly?

(@fantasai, @frivoal, @mrego)