Helpers: Single-pixel border helpers

[src-code]

From issue #76:

For the record: helpers.css (from another repo) has been updated with border classes meant to help when styling boxes with a single pixel border but those rules need to integrate Atomizer somehow.

More details from @thierryk:

border needs 3 values: width style color. We can get style borders the way we want with Atomizer by using those 3 but a common use case is to style border with a single pixel, so what we added to the helper classes are border declarations mixing both style and width

that way authors can do this: Bd Bdc-000 to get a black border around a box instead of having to go verbose with Atomic Bdc-000 Bds-s Bdw-1px

[thierryk]

@src-code what is this issue about exactly? The helpers for single pixel border are done already. In my opinion, all we need now is to open an issue (if not done already) to integrate most rules in that helpers.css file into Atomizer.

[src-code]

@thierryk This issue was to track that specific helper to be added to Atomizer's helpers (which are pending, of course). If you'd rather, we could make the issue more generic for simply creating a helpers ruleset in Atomizer, and assume that these helpers would just be part of that.

[thierryk]

@src-code Yes, I think that would make more sense to track the fact that helpers need to be integrated into Atomizer as a whole. With true/false flags in case people don't want them or want to cherry pick those rules.

[src-code]

Ok, created issue #96 to track helpers more generically.