1. Diagonal "UNDO" Stamp: Centered on completed cards, rotated -25°, semi-transparent overlay
2. Badge Colors Match Borders: Priority badges now use the same color as the left border (Critical=Red, High=Orange, Medium=Teal, Low=Green)
3. Subtle Completed Background: Very light gray tint instead of bright green
4. Click to Undo: Same behavior - clicking removes stamp and resets card to open state
☝️ Click the UNDO stamp to redo
✅ Ready to be completed again!
Tasks appear in the same order on all devices. Example: "First Floor Safety" always appears first.