Fix Streamlit use_container_width compatibility bug

app.py

@@ -629,7 +629,7 @@ with col_ctrl:
         
         col_node_btns = st.columns(2)
         with col_node_btns[0]:
-            if st.button("Add/Save Node", use_container_width=True):
+            if st.button("Add/Save Node"):
                 if node_id:
                     is_update = node_id in model.nodes
                     if is_update:
@@ -643,7 +643,7 @@ with col_ctrl:
                 else:
                     st.error("Short ID designation required.")
         with col_node_btns[1]:
-            if st.button("Delete Node", use_container_width=True):
+            if st.button("Delete Node"):
                 if node_id:
                     if model.delete_node(node_id):
                         st.rerun()
@@ -657,7 +657,7 @@ with col_ctrl:
         edge_path = st.text_input("Path (e.g., A -> B -> C)", key="edge_path")
         edge_style = st.selectbox("Connector Line Style", ["Straight", "Curved", "Dotted"], key="edge_style")
         
-        if st.button("Add Edges", use_container_width=True):
+        if st.button("Add Edges"):
             if edge_path:
                 success, msg = model.add_edge_path(edge_path, edge_style)
                 if success:
@@ -694,7 +694,7 @@ with col_ctrl:
         if model.edges:
             edge_labels = [f"{e.u} -> {e.v} ({e.style.title()})" for e in model.edges]
             del_edge_idx = st.selectbox("Select Edge to Delete", range(len(model.edges)), format_func=lambda i: edge_labels[i])
-            if st.button("Delete Selected Edge", use_container_width=True):
+            if st.button("Delete Selected Edge"):
                 model.remove_edge(del_edge_idx)
                 st.rerun()
         else:
@@ -704,11 +704,11 @@ with col_ctrl:
     with st.expander("Global Actions", expanded=True):
         col_actions = st.columns(2)
         with col_actions[0]:
-            if st.button("Auto-Layout", use_container_width=True):
+            if st.button("Auto-Layout"):
                 model.auto_layout()
                 st.rerun()
         with col_actions[1]:
-            if st.button("Clear All", use_container_width=True):
+            if st.button("Clear All"):
                 model.clear()
                 st.rerun()
                 
@@ -719,8 +719,7 @@ with col_ctrl:
             label="Download JSON Project File",
             data=json_data,
             file_name="flowchart_project.json",
-            mime="application/json",
-            use_container_width=True
+            mime="application/json"
         )
         
         uploaded_file = st.file_uploader("Upload JSON Project", type="json")
@@ -744,7 +743,7 @@ with col_canvas:
     flowchart_img.save(buffer, format="PNG")
     img_bytes = buffer.getvalue()
     
-    st.image(img_bytes, caption="Clean B&W Flowchart (Auto-cropped)", use_container_width=False)
+    st.image(img_bytes, caption="Clean B&W Flowchart (Auto-cropped)", use_column_width=False)
     
     # Download Button
     st.download_button(