feat(styles): one stylesheet source for react and svelte (#3350)

* feat(styles): create stylesheets for react and svelte based on one source

* refactor(styling): cleanup

* refactor(postcss): share a config

* refactor(postcss): replace env hack with env file

packages/react/src/container/NodeRenderer/index.tsx

@@ -4,7 +4,7 @@ import { internalsSymbol, errorMessages, Position, clampPosition, getPositionWit
 
 import useVisibleNodes from '../../hooks/useVisibleNodes';
 import { useStore } from '../../hooks/useStore';
-import { containerStyle } from '../../styles';
+import { containerStyle } from '../../styles/utils';
 import { GraphViewProps } from '../GraphView';
 import type { NodeTypesWrapped, ReactFlowState, WrapNodeProps } from '../../types';
 

packages/react/src/container/Pane/index.tsx

@@ -8,7 +8,7 @@ import cc from 'classcat';
 import { getNodesInside, getEventPosition, SelectionMode } from '@xyflow/system';
 
 import UserSelection from '../../components/UserSelection';
-import { containerStyle } from '../../styles';
+import { containerStyle } from '../../styles/utils';
 import { useStore, useStoreApi } from '../../hooks/useStore';
 import { getSelectionChanges, getConnectedEdges } from '../../utils';
 import type { ReactFlowProps, ReactFlowState, NodeChange, EdgeChange } from '../../types';

packages/react/src/container/ZoomPane/index.tsx

@@ -6,7 +6,7 @@ import { XYPanZoom, PanOnScrollMode, type Transform, type PanZoomInstance } from
 import useKeyPress from '../../hooks/useKeyPress';
 import useResizeHandler from '../../hooks/useResizeHandler';
 import { useStore, useStoreApi } from '../../hooks/useStore';
-import { containerStyle } from '../../styles';
+import { containerStyle } from '../../styles/utils';
 import type { FlowRendererProps } from '../FlowRenderer';
 import type { ReactFlowState } from '../../types';