<!DOCTYPE HTML><!-- Any copyright is dedicated to the Public Domain. http://creativecommons.org/publicdomain/zero/1.0/--><html><head><metacharset="utf-8"><title>Reference: splitting vertical writing-mode blocks</title><linkrel="author"title="Mats Palmgren"href="https://bugzilla.mozilla.org/show_bug.cgi?id=1328095"><styletype="text/css">body,html{padding:30px;margin:0;}.col{columns:2;column-gap:0;column-fill:auto;block-size:90px;inline-size:140px;border:1pxsolid;}.vl{writing-mode:vertical-rl;}x{display:block;break-inside:avoid;page-break-inside:avoid;vertical-align:top;inline-size:20px;block-size:20px;background:silver;}x:nth-of-type(2n){background:purple;}blue{display:block;inline-size:70px;border-block-start:25pxsolidblue;}grey{display:block;inline-size:70px;border-block-start:17pxsolidgrey;}</style></head><body><divclass="col vl"><divclass="inner"style="margin-left:40px"></div><blue></blue><x></x><x></x><grey></grey></div><divclass="col"><divclass="inner"style="margin-top:40px"></div><blue></blue><x></x><x></x><grey></grey></div><divclass="col vl"><divclass="inner"style="margin-left:40px"></div><blue></blue><x></x><x></x><divstyle="width:45px"></div><grey></grey></div><divclass="col vl"><divclass="inner"style="margin-left:40px"></div><blue></blue><x></x><x></x><divstyle="width:60px"></div><grey></grey></div></body></html>