<!DOCTYPE html>
<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/7660">
<style>
.target {
  display: grid;
  grid-auto-flow: column;
  position: relative;
  line-height: 0;
  font-size: 20px;
  inline-size: 300px;
  margin-block: 10px;
  padding: 10px;
  border: solid 3px;
  writing-mode: vertical-rl;
}

.inner {
  overflow: hidden;
  inline-size: 100px;
  block-size: 80px;
  margin: 10px;
  border: solid 5px;
  padding: 10px;
  font-size: 30px;
}

span {
  display: inline-block;
  width: 1