Removes support for old Safari flexbox syntax.

Autoprefixer applies the prefixes in the wrong order, so this removes support for older (also unsupported) Safari versions.
Fixes margin bug on detailed hero image copy.

The detailed version of the hero image copy had a right-margin on it, which caused it to push too far to the left. This update fixes that issue.
Merge branch 'master' of https://github.com/revoltpuppy/Evergreen into grid-system-fixing