code: function shade(percentage: number | string, color: string): string {
    if (color === 'transparent') return color
    return mix(parseFloat(percentage), 'rgb(0, 0, 0)', color)
  }
docs: Shades a color by mixing it with black. `shade` can produce
  hue shifts, where as `darken` manipulates the luminance channel and therefore
  doesn't produce hue shifts.
  
  @example
  // Styles as object usage
  const styles = {
  background: shade(0.25, '#00f')
  }
  
  // styled-components usage
  const div = styled.div`
  background: ${shade(0.25, '#00f')};
  `
  
  // CSS in JS Output
  
  element {
  background: "#00003f";
  }