CSS Backdrop Filter
Method of applying filter effects (like blur, grayscale or hue) to content/elements below the target 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.
css selector: `::backdrop`
css selector: `::backdrop`: support on `dialog` elements
css selector: `::backdrop`: fullscreen support