disable file upload for default data selection && remove css black color

app.py

@@ -70,6 +70,13 @@ def plot_umap(adata):
     return img
 
 
+def toggle_file_input(default_dataset):
+    if default_dataset != "None":
+        return gr.update(interactive=False)  # Disable the file input if a default dataset is selected
+    else:
+        return gr.update(interactive=True)  # Enable the file input if no default dataset is selected
+
+
 def main(input_file_path, species, default_dataset):
 
     # Get the current working directory
@@ -209,7 +216,7 @@ if __name__ == "__main__":
                 Upload a `.h5ad` single cell gene expression file and select the species (Human/Mouse). 
                 The demo will generate UMAP projections of the embeddings and allow you to download the embeddings for further analysis.
             </div>
-            <div style="margin-bottom:20px; color: black;">
+            <div style="margin-bottom:20px;">
                 <ol style="list-style:none; padding-left:0;">
                     <li>1. Upload your `.h5ad` file or select one of the default datasets (subset of 10x pbmc data)</li>
                     <li>2. Select the species</li>
@@ -232,6 +239,14 @@ if __name__ == "__main__":
         with gr.Row():
             species_input = gr.Dropdown(choices=["human", "mouse"], label="Select species")
             default_dataset_input = gr.Dropdown(choices=["None", "PBMC 100 cells", "PBMC 1000 cells"], label="Select default dataset")
+
+        # Attach the `change` event to the dropdown
+        default_dataset_input.change(
+            toggle_file_input,
+            inputs=[default_dataset_input],
+            outputs=[file_input]
+        )
+
         run_button = gr.Button("Run", elem_classes="run-button")
         
         # Arrange UMAP plot and file output side by side