1. :placeholder-shown CSS pseudo-class

    Input elements can sometimes show placeholder text as a hint to the user on what to type in. See, for example, the placeholder attribute in HTML5. The :placeholder-shown pseudo-class matches an input element that is showing such placeholder text.

  2. css selector: `:placeholder-shown`: support on non-`type="text"` elements (such as `type="number"` or `type="time"`)