Update app.py

app.py

@@ -19,7 +19,7 @@ end_date = st.date_input("Project End Date:", value=datetime.today() + timedelta
 
 num_activities = st.number_input("Number of Activities (Minimum 1):", min_value=1, value=5)
 
-activities = []
+activities =
 for i in range(num_activities):
     col1, col2 = st.columns(2)
     with col1:
@@ -28,9 +28,19 @@ for i in range(num_activities):
         activity_duration = st.number_input(f"Activity {i+1} Duration (days):", min_value=1, key=f"duration_{i}")
     activities.append({"Task": activity_name, "Duration": activity_duration})
 
-if st.button("Create Gantt Chart"):
+if st.button("Create Gantt Chart"): # The button is now correctly placed
     if not project_name:
         st.error("Please enter a project name.")
     elif any(not activity["Task"] for activity in activities):
         st.error("Please enter names for all activities.")
-    # Corrected line
+    elif start_date > end_date:
+        st.error("Start date cannot be after end date.")
+    else:
+        try:
+            df = pd.DataFrame(activities)
+            df['Start'] = pd.to_datetime(start_date)
+            df['Finish'] = df['Start']
+
+            for i in range(len(df)):
+                if i > 0:
+                    df.loc[i, 'Start'] = df.