Ok, after some time, here’s what I landed on:
.parent {
position: relative;
top: 0;
left: 0;
}
.image1 {
position: relative;
top: 0;
left: 0;
border: 1px red solid;
}
.image2 {
position: absolute;
top: 30px;
left: 30px;
border: 1px green solid;
}
<div class="parent">
<img class="image1" src="https://via.placeholder.com/50" />
<img class="image2" src="https://via.placeholder.com/100" />
</div>
As the simplest solution. That is:
Create a relative div that is placed in the flow of the page; place the base image first as relative so that the div knows how big it should be; place the overlays as absolutes relative to the upper left of the first image. The trick is to get the relatives and absolutes correct.