Update GOV.UK Design System to use GOV.UK Frontend 3.0

[aliuk2012]

What

GOV.UK Frontend 3.0 relates to WCAG 2.1 (Focus colour, colour platte updates and more).

Why

GOV.UK Design System needs to be updated to use GOV.UK Frontend 3.0 so that it can help support those changes and look consistent with the new styles

Who needs to know about this

Dave, Tim and developer

Further detail

Done when

• Test it with a pre-release of GOV.UK Frontend 3.0
• Fix any identified issues
• Potentially write up new documentation (Might not be necessary)

[36degrees]

I think this is either done or replaced by other cards.