<!DOCTYPE html> <html> <head> <title>Bug 1122366 - margin collapsing</title> <style type="text/css"> div { font: 40px/1em serif; height: 4em; } div.wrapper { margin: 10px; background: blue; border-left: green solid .5em; border-right: green solid 1.5em; } div.lr { -webkit-writing-mode: vertical-lr; writing-mode: tb-lr; /* IE11 */ writing-mode: vertical-lr; } div.rl { -webkit-writing-mode: vertical-rl; writing-mode: tb-rl; /* IE11 */ writing-mode: vertical-rl; } div.widthless { margin-right: 2em; width: 0; } </style> </head> <body> <div class="wrapper lr"> <div class="widthless"></div> <div class="widthless"></div> </div> <div class="wrapper rl"> <div class="widthless"></div> <div class="widthless"></div> </div> </body> </html>