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.
@AlasdairSwan it's really important to *never* paste together disparate parts of sentences. I can always find an example of a language that needs things in different orders.

I would be happy to go over i18n standards with you. Please put 30 min on my calendar when you are available. It is critically important that all engineers adhere to quality i18n standards, not the least because I spend a lot of time cleaning up after developers who make basic i18n errors.