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Do generic optimization first
Raise `@charset` rule

Fixes #21
Wring `font-weight`

This fixes #22.
Wring multiple values

This fixes #23, wrings value of following properties as possible:

  - `margin`
  - `padding`
  - `border-color`
  - `border-radius`
  - `border-spacing`
  - `border-style`
  - `border-width`

TODO: `background-position`
Wring `font-family` value

This fixes #24.
Use list helper