Allow str paths for loading css stylesheets

aiidalab_widgets_base/utils/loaders.py

@@ -1,32 +1,47 @@
+from __future__ import annotations
+
 from importlib.resources import Package, files
+from pathlib import Path
 
 from IPython.display import Javascript, display
 
 
-def load_css_stylesheet(package: Package, filename: str = ""):
+def load_css_stylesheet(
+    package: Package | None = None,
+    css_path: str | Path = "",
+    filename: str = "",
+):
     """Load a CSS stylesheet from a package and inject it into the DOM.
 
     Parameters
     ----------
-    `package` : `Package`
+    `package` : `Package`, optional
         The package where the CSS file is located.
+    `css_path` : `str` | `Path`, optional
+        The path to the folder where the CSS file is located.
     `filename` : `str`, optional
         The name of the CSS file to load.
-        If not provided, all CSS files in the package will be loaded.
+        If not provided, all CSS files in the package/folder will be loaded.
     """
-    root = files(package)
-
-    if filename:
-        filenames = [filename]
+    if package:
+        root = files(package)
+        filenames = (
+            [root / filename]
+            if filename
+            else [
+                root / path.name
+                for path in root.iterdir()
+                if path.is_file() and path.name.endswith(".css")
+            ]
+        )
+    elif css_path:
+        path = Path(css_path)
+        filenames = [path / filename] if filename else [*path.glob("*.css")]
     else:
-        filenames = [
-            path.name
-            for path in root.iterdir()
-            if path.is_file() and path.name.endswith(".css")
-        ]
+        raise ValueError("Either `package` or `path` must be provided.")
 
     for fn in filenames:
-        stylesheet = (root / fn).read_text()
+        stylesheet = fn.read_text()
         display(
             Javascript(f"""
                 var style = document.createElement('style');