Interface FillStyle

The color of the fill, which can be a CSS color string (e.g., '#000000' for black) or undefined for a default color. If the color is undefined, the rendering logic may choose a default fill color based on the node's properties or theme.

The gradient value of the fill, which can be a GradientValue object or undefined for no gradient. If the gradient value is undefined, the rendering logic may choose a default gradient based on the node's properties or theme.