code: function(options) {
          var focusLayerRule = classRule(classNameConst.LAYER_FOCUS_BORDER).bg(options.border);
          var editingLayerRule = classRule(classNameConst.LAYER_EDITING).border(options.border);
  
          return builder.buildAll([focusLayerRule, editingLayerRule]);
      }
docs: Generates a css string for focused cell.
  @param {Object} options - options
  @returns {String}