Fill Background Color

Sets the color used to fill the border when fit=fill or fit=fillmax is active and fill=solid.

fill-color accepts a hex color in RRGGBB or RGB format without the # prefix (e.g. 203040 for a dark slate). The default is 000000 (black).

fill-color is applied when fill=solid (the default fill type). It is also used as a silent fallback for fill=image — if the image URL fails to fetch or is not a supported format, the border renders onto fill-color instead of erroring. It is ignored when fill=blur.