Project: sequelize
Task (challenging): 1) Add the .pay-my-order button to /order/:order-id; Button is visible when the status is 'Pending payment' 2) When .pay-my-order is clicked, the status of the order becomes 'Finished', and the Coin is paid by current user; 3) Decrease product quantity; 4) If payment fails, update the order status to 'Failed'. 5) Create CSS files to beautify CSS. Constraint: DO NOT use a third-party UI library.