Feature: Component add top level navigation to header

[htmlandbacon]

What

Build first version of top level navigation component based on prototype discussion.

See #513 for design.

Done when

Suggested that two versions will be provided for this with the no-javascript version falling back to default behaviour

• standard header, adaptive to maximum header width
• enhancement of Javascript version

Deliverables:

• component spec
• macro component
• unit tests
• sass
• javascript
• examples
• Compatibility testing evidence
• Recouple components

Outcomes

A releasable, tested header navigation.

Related stories

• Navigation Components #176
• Improvements to header component. #560

[simoneduca]

Ask @mitz-lad details on mobile view

[jonhurrell]

Decision on decoupling header from main navigation

Actions

• Team agreed to couple and encapsulate the header and main navigation component together.
• For discoverability and clarity of guidance, we'll treat them as related but separate concerns on the main site.

Background

If conditions or constraints on fragmented service changes we may need to separate them, to be able to offer more flexibility and widen the scope to meet those challenges. @mitz-lad Proposed the overlap between them could be easily mitigated by moving the mobile reveal within the navigation bar itself.

Topics covered in decision

• Discoverability on main site
• Guidance coupling vs seperation clarity
• Tracking adoption
• Encapsulation of concerns vs composition flexility (to meet those conditions mentioned above)
• Predictability of changes/maintenance with interdependency of design and engineering assets.