Details

On a few instances we use --visible in the Tour Kit main stylesheet.

• Let's refactor these to match the more recommended Calypso convention for such modifiers (e.g. is-visible).
• Also rethink whether is-hidden would be more suited in some cases e.g. on the main tour-kit-frame class.

Checklist

• --visible -> is-vsible (or is-hidden where more appropriate)
• Ensure Storybook demos work as expected
• Ensure ETK Welcome Tour works as expected
• One of the modifiers addresses a flicker when the tour goes from step to step (see Tour Kit: Update spotlight effect, other fixes/cleanup #58854), so ensure this is handled

Related

No response