css/css-scroll-snap/snap-after-initial-layout/writing-mode-horizontal-tb.html

<!DOCTYPE html>
<title>
  Scrollers should snap to the closest snap point on initial layout
  (using 'writing-mode: horizontal-tb')
</title>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap/#re-snap" />
<link rel="match" href="snap-after-initial-layout-ref.html" />
<style>
div {
  position: absolute;
  margin: 0;
}

#scroller {
  height: 500px;
  width: 500px;
  overflow: hidden;
  scroll-snap-type: both mandatory;
  writing-mode: horizontal-tb;
}

#close-target {
  width: 200px;
  height: 200px;
  border: solid green 50px;
  top: 50px;
  left: 150px;
  margin: 50px;
  background-color: green;
  scroll-snap-align: start end;
}

#far-target {
  width: 300px;
  height: 300px;
  top: 100px;
  left: 500px;
  background-color: red;
  scroll-snap-align: start end;
}

.area {
  width: 2000px;
  height: 2000px;
}
</style>

<div id="scroller">
  <div class="area"></div>
  <div id="close-target"></div>
  <div id="far-target"></div>
</div>