The exported SVG's 4 edge labels (no/yes/approve/decline) had two extra,
non-adaptive background-color declarations stamped onto their wrapper
divs by the draw.io exporter (flat #ffffff, and an undefined
var(--ge-adaptive-bg) CSS variable that falls back to #ffffff) -
independent of both the .drawio source content and the export dialog's
Appearance setting (tested Automatic and Light, both showed it).
Surgically stripped just those two declarations from the exported SVG,
verified count (4+4 removed, 0 remaining), confirmed the correct
adaptive span background (light-dark(white, #1C1D1E)) and every other
color in the diagram were untouched, confirmed still valid XML.