How to check css in unit test

 describe('Link', () => {

 makeElement = () => {

  let element = angular.element('<textarea id="addnote" vnc-auto-resize style="height: 0px"></textarea>');
  _$compile_(element)($rootScope);
  return element;
};
// Link specs
it('height should be define and enable', () => {
  let element = makeElement();
  expect(element).to.have.height(30px');
});

  });

this return error on height. how to check height in unit test ?