diff --git a/package.json b/package.json
index 3bb28f3..81b6602 100644
--- a/package.json
+++ b/package.json
@@ -33,7 +33,6 @@
 		"@types/css-tree": "^2.3.11",
 		"@types/node": "^25.9.1",
 		"@types/sanitize-html": "^2.16.1",
-		"css-tree": "^3.2.1",
 		"eslint": "^10.0.3",
 		"eslint-config-prettier": "^10.1.8",
 		"eslint-plugin-svelte": "^3.15.2",
@@ -57,6 +56,7 @@
 		"@atproto/oauth-client-node": "^0.4.1",
 		"@dasl/tiles": "^1.3.0",
 		"better-sqlite3": "^12.10.1",
+		"css-tree": "^3.2.1",
 		"marked": "^18.0.5",
 		"sanitize-html": "^2.17.5"
 	},
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index fedb92f..c0d0f9d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -34,6 +34,9 @@ importers:
       better-sqlite3:
         specifier: ^12.10.1
         version: 12.10.1
+      css-tree:
+        specifier: ^3.2.1
+        version: 3.2.1
       marked:
         specifier: ^18.0.5
         version: 18.0.5
@@ -83,9 +86,6 @@ importers:
       '@types/sanitize-html':
         specifier: ^2.16.1
         version: 2.16.1
-      css-tree:
-        specifier: ^3.2.1
-        version: 3.2.1
       eslint:
         specifier: ^10.0.3
         version: 10.5.0(jiti@2.7.0)
diff --git a/vite.config.ts b/vite.config.ts
index e0b99de..9e01e24 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -18,6 +18,12 @@ export default defineConfig({
 		__TWINKL_VERSION__: JSON.stringify(twinklVersion)
 	},
 	plugins: [tailwindcss(), sveltekit()],
+	ssr: {
+		// css-tree loads its data files at runtime via createRequire('../data/patch.json').
+		// Bundling it into the server chunk breaks that relative path, so keep it external
+		// and let Node resolve it from node_modules where the data files live.
+		external: ['css-tree']
+	},
 	server: {
 		host: '127.0.0.1',
 		port: 5179