1. Dialog element

    Method of easily creating custom dialog boxes to display to the user with modal or non-modal options. Also includes a `::backdrop` pseudo-element for behind the element.

  2. css selector: `::backdrop`

  3. css selector: `::backdrop`: support on `dialog` elements

  4. css selector: `::backdrop`: fullscreen support

  5. css selector: `::backdrop`: backdrop elements inherit their values from its originating element

  6. css selector: `::backdrop`: support on popovers