v0.9.0

New features

• Add set-css-variable mixin and get-css-variable function to handle the prefix using CSS variables.

Improvements

• Add $form-check-margin variable to control the .form-check vertical offset.
• Modify layout-* mixins to accept a shorthand value of for spacer from the $spacers map (now you can use any defined key like m, l, xl and so on).

Bugfix

• Fix text-ellipsis mixin bug.
• Fix null prefix variable generating. Now you can null its value correctly under the $settings map.