Like ink spreading in a pool of water, the color moves outward from a center. It creates a glow-like background or a clearly centered field of color.
`colorA` is the center color and `colorB` is the outer color. Move `center` to move the origin; increase `radius` to carry the transition farther across the canvas (default 1, range 0–2). Set `repeat` above 1 to add concentric bands (default 1, range 1–20).
This layer fills the canvas by itself and needs no input beneath it. Moving the center to an edge can concentrate the brightest area there, so check contrast where text will sit. Too many repeated bands can compete with the content.
When to use
Use it for an off-center glow, a focused color field, or concentric rings. Avoid it when repeated bands would compete with body text.