为什么我的TinyMCE隐藏文本区域表现正常？

tinymce.init({
  selector: 'textarea',
  height: 500,
  plugins: [
    'advlist autolink lists link image charmap print preview anchor',
    'searchreplace visualblocks code fullscreen',
    'insertdatetime media table contextmenu paste code'
  ],
  toolbar: 'insertfile undo redo | styleselect | bold italic | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | link image | print preview media fullpage | forecolor backcolor emoticons | code',
  content_css: '//www.tiny.cloud/css/codepen.min.css'
});