A deep-partial of ChartTheme — every leaf optional, arrays kept whole
(so axis.gridDash / annotation.depth replace rather than merge
element-wise). The shape a cssVarTheme resolver returns: name only the
slots you're driving from CSS, everything else falls through to the base.
A deep-partial of ChartTheme — every leaf optional, arrays kept whole (so
axis.gridDash/annotation.depthreplace rather than merge element-wise). The shape a cssVarTheme resolver returns: name only the slots you're driving from CSS, everything else falls through to the base.