The bottom box scrolls along when the mobile end of the pop-up window scrolls

Solution Solutions

When pop-up popup window, set window outermost position to fixed, so that window will not scroll, when the popup window is closed, set the window body positioning as Static,window can be re-scrolling.

In addition, when the setting is fixed on the popup to the top of the window, you can get the scrolltop by JS, fixed set top negative.

When you close the window will also return to the top, you can also get the scrolltop by JS, fixed set scrolltop value.

The bottom box scrolls along when the mobile end of the pop-up window scrolls