может быть, вам нужно использовать JavaScript следующим образом:
firstdiv =document.querySelector(".first");
secondiv =document.querySelector(".second");
thirdiv = document.querySelector(".third");
const fheight = firstdiv.offsetHeight;
const sheight = secondiv.offsetHeight;
secondiv.style.top= `${fheight}px`;
thirdiv.style.top= `${fheight+sheight}px`;
body {
margin:0;
min-height:200vh;
border:2px solid;
}
.first {
height:50px;
background:red;
position:sticky;
top:0;
}
.second {
height:60px;
background:blue;
position:sticky;
}
.third {
height:80px;
background:green;
position:sticky;
}
<div class="first"></div>
<p>lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum</p>
<div class="second"></div>
<p>lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum</p>
<div class="third"></div>
<p>lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum lorem ipsum</p>