Fix for border-style in preflight

[kylemilloy]

Resolves specific issue with Google Maps as tracked here: #564

Adds the following to preflight.css:

* {
border-style: inherit;
}

Which prevents some weird bugs when you're trying to make CSS triangles via border-width and using absolute positioning.

This will cause API breaking changes to how classes like @apply border; work however (you'll have to manually set the border-style).

[adamwathan]

This unfortunately breaks the ability to just add border to a div and have a border appear, since those utilities only adjust the border-width.

Our border reset styles are admittedly quite opinionated in this regard, but no plans to change them for this because the trade-off is too annoying :/

The recommended fix is to add your own CSS to target and fix the map element, as discussed in this earlier issue:

#484

[kylemilloy]

Fair enough.