Thank you for the code which works very well on an iPhone.
However, it needs a tweak to work on iPads. I found this worked:
increase max-width to 2732px (for 12.9 inch iPads)
and padding-bottom to 450px.
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0,user-scalable=0"/>
<style>
@media screen and (max-width:2732px) {
.sqs-modal-lightbox-content .lightbox-inner .lightbox-content {
padding-bottom: 450px !important;
}
}
</style>