AFAIK, CSS cannot affect the DOM tree. So, display: none just says the element should not be displayed, not that it should cease to exist. Style/structure separation and all that.

Take a look at the example form below. When you select one of the options under the "Which semester are you applying for?" heading, the corresponding Text component appears. The checkbox group has ...

Then, the classNames for the form elements are swithced with JavaScript. Marko also uses JavaScript to preloaded the custom images. Here's an example of his technique from the Nacional news magazine: ...