Constant EMBEDDED_THEME 

const EMBEDDED_THEME: &str = "{\n  \"ShapeFill\": \"B02\",\n  \"ShapeStroke\": \"B04\",\n  \"ShapeTitle\": \"B05\",\n  \"LockedShapeFill\": \"B03\",\n  \"LockedShapeTitle\": \"B04\",\n  \"ShapeType\": \"B04\",\n  \"LockedShapeType\": \"B03\",\n  \"LockedHintIcon\": \"B04\",\n  \"AccentDefault\": \"B04\",\n  \"Accent0\": \"B08\",\n  \"Accent1\": \"B09\",\n  \"Accent2\": \"B0A\",\n  \"Accent3\": \"B0B\",\n  \"Accent4\": \"B0C\",\n  \"Accent5\": \"B0D\",\n  \"Accent6\": \"B0E\",\n  \"Accent7\": \"B0F\",\n  \"TextBoxFill\": null,\n  \"TextBoxStroke\": null,\n  \"AreaStroke\": \"B06\",\n  \"RouteNormal\": \"B04\",\n  \"RouteSelected\": \"B07\",\n  \"RouteHighlighted\": \"B06\",\n  \"RouteInProgress\": \"B05\",\n  \"RouteProposedEndpoint\": \"B03\",\n  \"PinStem\": \"B04\",\n  \"PinText\": \"B05\",\n  \"PinTag\": \"B05\",\n  \"PinStemSelected\": \"B07\",\n  \"PinTagSelected\": \"B07\",\n  \"PinLabelPlaceholder\": \"B04\",\n  \"DragPreviewStroke\": \"B04\",\n  \"DragActiveFill\": \"B02\",\n  \"DragActiveStroke\": \"B0F\",\n  \"EdgeDragPreview\": \"B04\",\n  \"SelectionFrame\": \"B09\",\n  \"SelectionFrameOutline\": \"B0E\",\n  \"ControlHandleFill\": \"B07\",\n  \"ControlHandleStroke\": \"B00\",\n  \"WaypointFill\": \"B0B\",\n  \"ResizeCornerFill\": \"B04\",\n  \"ResizeCornerStroke\": \"B07\",\n  \"ResizeCornerActiveFill\": \"B0C\",\n  \"ResizeCornerActiveStroke\": \"B07\",\n  \"ImageDragBox\": \"B0D\",\n  \"MarqueeFill\": \"B0F\",\n  \"NewBlockPreviewStroke\": \"B0D\",\n  \"NewPinPreviewFill\": \"B0D\",\n  \"NewPinPreviewStroke\": \"B07\",\n  \"RouteStartTarget\": \"B0B\",\n  \"CanvasBackground\": \"B00\",\n  \"GridLine\": \"B02\",\n  \"PinDragIndicator\": \"B04\",\n  \"DebugMark\": \"B08\",\n  \"AlignmentGuide\": \"B07\"\n}";

The role → base overrides baked into the binary, written by the theme editor (--theme-editor) on exit. See Theme::from_embedded.