Fix namespacing issue for jeet-replace-nth() call
Merge pull request #318 from clear-y/jc/fix-namespacing-issue

Fix namespacing issue for jeet-replace-nth() call
Improve code consistency

- Change all vars to lowercase-with-dashes
- Remove back-ticks from comment
Merge pull request #319 from clear-y/jc/code-conventions

Variable styling and a minor comment change
Add offset mixin

- Takes a ratio & gutter
- Can also specifiy if it's a column or span