The CSS from the [learn theme's notice shortcode](https://learn.netlify.app/en/shortcodes/notice/) can be used to style the notification bar instead of doing it ourselves.
I set the current one to be a "Tip", but it could be a "Note", "Info", or "Warning".
Testing Done:
Delete the cookie, and opened a page that showed the notification. Clicked the X and the notification went away as expected, and the cookie was set.