Anchor tags should not use an explicit font size

[theadamparker]

Currently <a> tags set an explicit font size intended to match paragraph font size in the design system. However this poses issues when the stylesheet is applied to content not built with the design system (e.g. Exposure) and shouldn't be a requirement.

Suggested fix is to remove the font-size declaration here. This will require regression testing to ensure there are no unintended changes.