Refactor _colors.sass.

@import palette

// Calc color by base color name and level.

@function get-color($name, $level)

    $color: map-get($palette, $name)

    $mix-color: if($level < 0, black, white)

    @return $color

// Add foreground and background classes for all colors.

@each $color-name in map-keys($palette)

    @for $i from -5 through 5

        .bg-#{$color-name}-#{map-get($shade-names, $i)}

        .fg-#{$color-name}-#{map-get($shade-names, $i)}

            color: get-color($color-name, $i)

.bg-black

    background-color: black

.bg-white

    background-color: white

.fg-black

    color: black

.fg-white

    color: white

// Add black and white.

@each $color in black, white

    .bg-#{$color}

        background-color: $color

    .fg-#{$color}

        color: $color