Correctly Fix style sheet for `data-card`'s `footer a` to avoid affecting other parts.
Correctly Fix style sheet for `data-card`'s `footer a` to avoid affecting other parts.

(Follow up of bcf6c3d78ca6e032aa4754dbb8b7f4f9f7426f74)

uwdata/vega-lite-ui,vega/vega-lite-ui,uwdata/vega-lite-ui,vega/vega-lite-ui,vega/vega-lite-ui,uwdata/vega-lite-ui