Embedded Page tracking issue

[ashleygwilliams]

design

• migrate to tachyons
  • top-level heading – not started
  • get-started.hbs – not started
  • pitch.hbs – not started
  • showcase.hbs – not started
  • testimonials.hbs – not started
• responsive styling pass

[jamesmunns]

Note, once rust-lang/rust#56291 lands we should update links to the stable embedded book

[skade]

Migrated to Tachyons, along with responsive styling.