Normalize import path for emitted css files by rollup-plugin (#710)

Co-authored-by: mattcompiles <[email protected]>

Author: riccardoperra

.changeset/kind-zoos-cover.md

@@ -0,0 +1,5 @@
+---
+'@vanilla-extract/rollup-plugin': patch
+---
+
+Normalize import path for emitted css files

packages/rollup-plugin/src/index.ts

@@ -7,7 +7,9 @@ import {
   getSourceFromVirtualCssFile,
   virtualCssFileFilter,
 } from '@vanilla-extract/integration';
-import { relative, normalize, dirname } from 'path';
+import { posix } from 'path';
+
+const { relative, normalize, dirname } = posix;
 
 interface Options {
   identifiers?: IdentifierOption;