Lo Kim

also another Card variation: * border

[Commit](https://github.com/Shopify/polaris/pull/7530/commits/3a1df3f4e33c795c9468d152955b81bb088d84b2) with updates

[Commit](https://github.com/Shopify/polaris/pull/7530/commits/06a56465be802eb810683deda43cf2707a65ffd9) to apply these changes

This was updated with the [PR](https://github.com/Shopify/polaris/pull/7546) to add responsive styling to the `headingLg` variant.

Closing this in favor of the [second prototype](https://github.com/Shopify/polaris/pull/7279) where we explored using `Box` in `Toast` without the `className` prop on `Box`. We preferred that prototype over this one due to...

[Commit](https://github.com/Shopify/polaris/pull/7530/commits/9b51fce36770a027b954be72da82b819e21bdf53) with updates

/snapit

[Commit](https://github.com/Shopify/polaris/pull/7530/commits/52fbc125361abeaa91bca2fedc6db35d084026b3) with updates

Closing because we're tracking the work in issue #6901

/snapit