code: function(options) {
          var tableRule = classComposeRule(' .', [
              classNameConst.SHOW_LSIDE_AREA,
              classNameConst.LSIDE_AREA,
              classNameConst.HEAD_AREA,
              classNameConst.TABLE
          ]).verticalBorderStyle(options, 'right');
          var cellRule = classRule(classNameConst.CELL_HEAD)
              .bg(options.background)
              .border(options.border)
              .borderWidth(options)
              .text(options.text);
  
          return builder.buildAll([
              tableRule,
              cellRule
          ]);
      }
docs: /*
  Generates a css string for head cells.
  @param {Object} options - options
  @returns {String}