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.
While doing the JS test refactor, I changed `isActive` to `json.loads(el.data('is-active'))` so it's a bool instead of a string. That seems to have gotten lost in the rebase, but I think it's the right way to go, since `isActive` should be a boolean.