section { position: relative } /* For the `absolute`. */

section::after {
	color: white;
	content: 'Appears in front!'; /* Give us an element to work with. */
	inset: 2em;
	position: absolute;
	padding: 1em;
}

section:first-child::after {
	backdrop-filter: blur(0.5rem); /* `blur` is a common use. */
	background-color: color-mix(in srgb, #333, transparent) /* Shade it. */
}

section:nth-child(2)::after {
	background-color: tomato;
	mix-blend-mode: multiply; /* Just like Photoshop/Figma! */
}

section:nth-child(3)::after {
	backdrop-filter: invert(1);
	background-color: deepskyblue;
	mix-blend-mode: multiply; /* You can do crazy combinations. */
}