It looks like a diamond-shaped glow spreading in four directions from a center. Compared with a radial gradient, it gives the background more defined straight edges and corners.
`colorA` is the center color and `colorB` the outer color. Increase `size` to let the center color cover more area (default 0.7, range 0.01–2). Raise `roundness` from 0 toward 1 to morph the sharp diamond toward a square (default 0, range 0–1). Set `repeat` above 1 to repeat diamond or square bands outward (default 1, range 1–16).
This layer fills the canvas on its own and needs no image input. Its crisp edges can visually compete with thin lines or text above it, so check contrast and spacing when using it as decoration. Too many repeated bands can make the pattern compete with the content.
When to use
Use it for geometric backgrounds, a center-to-corner color field, or a square-like glow. Avoid it when the content needs a very quiet, unobtrusive background.