fix(feature-card): don't provide FeatureCard's href to ResourceC…

[jendowns]

Closes #517

As shown in #517, the FeatureCard currently takes an href and then adds that URL both a wrapper anchor element and to the inner ResourceCard component, which subsequently renders its own anchor element. As a result, the FeatureCard has nested anchors, which is invalid markup & generates a console error.

I propose a couple changes to fix this -- namely:

• the FeatureCard should not share its href value with the ResourceCard, as that is not necessary.
• the ResourceCard should render as a div if no href is provided (similar change to fix(image-card): render as div if no href is provided #515)

With these 2 changes, the FeatureCard will only render one anchor (the primary wrapper).

Changelog

New

• add focus styles to FeatureCard

Changed

• if no href is provided to ResourceCard, render as a div
• FeatureCard no longer passes its href value down to the inner ResourceCard

[vercel]

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[jendowns]

Tagging @dakahn 👍

[jendowns]

Thanks @vpicone -- I just updated the focus outline to be 2px, but I left out an offset rule. Given the wrapping div where the outline has to be applied (due to margins etc), a negative offset would not be visible.