Hi,
The best way to deal with fixed scrollable containers (like this popup) is to change the results layout from the default “hover” to a block. Since you have added access, I logged in and changed that for you. Now the results container is simply printed below the search bar, and does not hover over the content, but is positioned nicely without generating gaps from incorrect scroll heights.
The height issue can be addressed with a small custom CSS snippet:
.asp_r_1 {
max-height: 65vh;
}
Apply this code to your theme custom CSS field (if it supports it) or use the custom CSS field on the search plugin back-end.
You may need to change this to your exact case, but this will prevent the results box being larger as the overall 65% screen height.