Whenever We Click On ‘floating Cart Icon’ then Cart opened but backgroud screen comes ‘Bottom to Top’

Dear Sir, I just bought yours item by yesterday. But I find some issue with your Item.

My Query:
Whenever We Click On ‘floating Cart Icon’ then Cart opened but backgroud screen comes ‘Bottom to Top’ . If u are on footer section so when u click on ‘Cart’ Icon then cart opened successfully but at background ‘Header’ Section Comes.

Let Me Explain with example: Suppose u opened shop page(Which has 1st Banner Section