自动折扣按照固定金额进行优惠

https://wq.slquality.xyz/zh-hans-cn-hk/products/%E8%87%AA%E5%8A%A8%E6%8A%98%E6%89%A3%E6%8C%89%E7%85%A7%E5%9B%BA%E5%AE%9A%E9%87%91%E9%A2%9D%E8%BF%9B%E8%A1%8C%E4%BC%98%E6%83%A0