如果沒有圖的話，就只顯示背景圖
OPEN - #14: Coimotion API修改調整 
https://github.com/soon530/Bukr/issues/issue/14
沒圖載入預設的錯誤圖
OPEN - #14: Coimotion API修改調整 
https://github.com/soon530/Bukr/issues/issue/14
調整書單封面比例
OPEN - #14: Coimotion API修改調整 
https://github.com/soon530/Bukr/issues/issue/14