1article {
2  background:
3    linear-gradient(var(--bg), var(--bg)) padding-box,
4    radial-gradient(
5        100px 100px at calc(var(--x) * 1px) calc(var(--y) * 1px),
6        red 75%,
7        transparent
8      )
9      border-box,
10    hsl(0 0% 50% / 0.5);
11  background-blend-mode: hard-light;
12  background-attachment: fixed;
13  border: 4px solid transparent;
14}