Add theme parameter to the html exporter

app.py

@@ -26,6 +26,7 @@ async def convert(req: Request):
     if not url:
         raise HTTPException(400, "Param url is missing")
     print("\n===", url)
+    theme = req.query_params.get("theme")
     r = await client.get(
         url,
         headers={"Authorization": f"Bearer {os.environ.get('HF_TOKEN')}"},
@@ -57,6 +58,7 @@ async def convert(req: Request):
         )
 
     print(f"Input: nbformat v{notebook_node.nbformat}.{notebook_node.nbformat_minor}")
+    html_exporter.theme = "dark" if theme == "dark" else "light"
     body, _ = html_exporter.from_notebook_node(notebook_node)
     # TODO(customize or simplify template?)
     # TODO(also check source code for jupyter/nbviewer)