Add focus-indicator to SubHeadline component

[amoore108]

Overall changes

• Adds focus-indicator to subheadline component, which will be used mostly with the JumpTo component
• Changes spacing above and below subheadlines from padding to margin to allow focus-indicator to display correctly

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[karinathomasbbc]

LGTM

[greenc05]

This looks good though have we just thought about this in isolation and not the functionality? e.g. Have we considered the space above the heading when the user actions a link, ideally there would be a small amount of breathing space above the heading that is viewable

[amoore108]

This looks good though have we just thought about this in isolation and not the functionality? e.g. Have we considered the space above the heading when the user actions a link, ideally there would be a small amount of breathing space above the heading that is viewable

I see what you mean. Let me have a look and see if theres something that can be done about that. Thanks for the suggestion 👍

EDIT: I'll see if its possible to do with shifting content.

[greenc05]

If we can add .5rem padding above and below (and take away that from the margin) that would be better I think? (Like in the screen shot) Though obvs we don't want to mess up the article spacing