Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.21)
// Compass (v1.0.3)
// ----

// Define theme variables

$themes: (
  default: ( // default theme
    bg-color: white,
    text-color: black,
  ),
  dark: (
    bg-color: black,
    text-color: white,
  ),
  colorful: (
    bg-color: green,
    text-color: orange,
  )
);


// Mixins and functions defined once

@mixin themify() {
  // Iterate over the themes
  @each $theme-name, $theme in $themes {
    $current-theme: $theme !global;
    @if $theme-name == 'default' {
      @content;
    } @else {
      .theme-#{$theme-name} & {
        @content;
      }
    }
  }
}

@function theme-get($key, $theme: $current-theme) {
  $ret: map-get($theme, $key);
  @if not $ret {
    @error 'Your theme doesn\'t have a value for `#{$key}`.';    
  }
  @return $ret;
}

// This is how you use your themes

.example{
  padding: 10px;
  @include themify {
    background: theme-get(bg-color);
    color: theme-get(text-color);
  }
}

SassMeister-output.css

.example {
  padding: 10px;
  background: white;
  color: black;
}
.theme-dark .example {
  background: black;
  color: white;
}
.theme-colorful .example {
  background: green;
  color: orange;
}