ECOM-811 design and layout changes

@wedaly @stephensanchez @rlucioni here are the style and text updates. Unfortunately I had to use teh dreaded !important in my Sass to override some ridiculously specific selectors, but after the A/B test we can clean this up by removing the legacy styles.
Why is "Dashboard" capitalized here? That's odd. Also it was not capitalized originally, at L40.

If you can revert to the original capitalization, you will save translator effort as exising translations of the existing string will be preserved. Capitalizing "Dashboard" will break existing translations.