checkboxes do have a third 'indeterminate' state[0], but you can't activate it manually. it's basically 'null' rather than an affirmative 'true'/'false'. [0]:

checkboxes do have a third 'indeterminate' state[0], but you can't activate it manually. it's basically 'null' rather than an affirmative 'true'/'false'. [0]: https://developer.mozilla.org/en-US/docs/Web/CSS/:indeterminate https://developer.mozilla.org/en-US/docs/Web/CSS/:indetermin...