Day 41: custom properties and url()s

from blog Manuel Matuzović - Blog, | ↗ original
↗ original
Let’s say you want to swap the background image of an element based on a certain condition, like whether it’s pressed, using custom properties.button { --background-image: "/not-pressed.svg"; background: url(var(--background-image)); } button[aria-pressed="true"] { --background-image: "/pressed.svg"; } This looks fine, but it doesn't work...