nightwatchjs - How to detect hidden html elements?

There is a form with checkbox and input fields

Checkbox looks(looks custom style) hidden in browser view, hidden option by css (opacity:0 ) example

So nightwatchjs couldn't detect checkbox is exist or not

How to solve this scenario ?

formFieldsExist:function(){
  return this
             .assert.visible('#name')
             .assert.visible('#yesOrNo')
             .pause(2000)
}

1) How to detect hidden elements are exist or not ?

2) If there solution, How can detect checkbox status(true or false) ?