Mini cart problem

Hi everyone.

I am using greenshift theme to make a commercial website. I am of course having a problem with my header.

Specifically when I use mini cart on header. At the same time, if I leave the header sticky on top, there will be a problem that the mini cart cannot be closed when scrolling the web page down.

Here is my website: palmer.vn

The page I need help with: [log in to see the link]