anchor.diff:      });
   
       test('simple_css3_var_no_polyfill', () {
  -      String css = '''
  +      final input = '''
   :host {
     --test-color1: red;
   }
   body {
     color: var(--test-color1);
   }''';
  -      StyleSheet sheet = compile(css);
  -
  -      expect(printStyleSheet(sheet, pretty: false),
  -          ':host { --test-color1: red; } body { color: var(--test-color1); }');
  -    });
  -
  +      final generated =
  +          ':host { --test-color1: red; } body { color: var(--test-color1); }';
  +
  +      checkNoPolyfill(input, generated);
  +    });
  +
  +    // css3 vars not working
       test('simple_css3', () {
  -      // css3 vars not working
  -      String css = '''
  -:host {
  +      String css = '''
  +:root {
     --test-color1: red;
   }
   body {
     color: var(--test-color1);
   }''';
  -      StyleSheet sheet = compile(css,
  -          options: new PreprocessorOptions(polyfill: true), polyfill: true);
  -
  -      expect(printStyleSheet(sheet, pretty: false),
  -          ':host { --test-color1: red; } body { color: ; }');
  +      // We should have: checkPolyfill(css, ':root { } body { color: red; }')
  +      checkPolyfill(css, ':root { --test-color1: red; } body { color: ; }');
  +    });
  +
  +    test('simple_var', () {
  +      // simple var implementation
  +      String css = '''
  +:root {
  +  var-test-color1: red;
  +}
  +body {
  +  color: var(test-color1);
  +}''';
  +
  +      final generated = ':root { } body { color: red; }';
  +
  +      final generatedPretty = '''
  +:root {
  +}
  +body {
  +  color: #f00;
  +}''';
  +      checkPolyfill(css, generated);
  +      checkPrettyPolyfill(css, generatedPretty);
       });
   
       test('nested_rule', () {
  
positive.code: 
        expect(printStyleSheet(sheet, pretty: false),
            '.red,.blue { color: red; } .blue { width: 0; }');
      });
  
      test('scss_media_query_var_and_extend', () {
  
negative.code:           compileCss('@color1: red; body { color: @color1; }', pretty: false),
            'body { color: red; }');
      });
      test('less_@', () {
        String css = 'body{opacity:1}';
        expect(compileCss(css), compileCss(css, polyfill: false));
        css = '@color1: red; body { color: @color1; }';
        expect(compileCss(css), isNot(compileCss(css, polyfill: false)));
      });
  
      test('less_var', () {
        final input = '''
  @color-background: red;
  @color-foreground: blue;
  .test {
    background-color: var(color-background);
    color: var(color-foreground);
  }
  ''';
        final generated = '''
  var-color-background: #f00;
  var-color-foreground: #00f;
  
  .test {
    background-color: var(color-background);
    color: var(color-foreground);
  }''';
        checkCompile(input, generated, pretty: true);
      });
    });
    //YachtTransformer transformer;
    group('csslib_exp', () {
  