fix(canvas): 画布浮层 - 修复小地图定位并弱化卡片边界

web/src/components/canvas/canvas-node.tsx

@@ -291,7 +291,8 @@ export const CanvasNode = React.memo(function CanvasNode({
                 data-state={data.metadata?.status || (isActive ? "active" : isRelated ? "related" : "idle")}
                 style={{
                     background: hasImageContent || hasVideoContent ? "transparent" : theme.node.fill,
-                    border: isComposerNode || isSelected ? "0" : `1px solid ${theme.node.edge}`,
+                    // 固定占位但不绘制描边，避免聚焦切换时边框宽度变化造成白边跳动。
+                    border: isComposerNode ? "0" : "1px solid transparent",
                     boxShadow: isComposerNode ? "none" : isSelected || hovered ? theme.node.hoverShadow : theme.node.shadow,
                 }}
                 onMouseDown={(event) => onMouseDown(event, data.id)}