<html style="-webkit-writing-mode: horizontal-bt"><body style="border:2px solid black; height:500px">
<div style="margin-bottom:1em; height:200px;border:2px solid maroon"><div style="float:right;width:100px;height:100px;background-color:lime"></div>
Here is some text in a horizontal-bt block flow.  The block direction is bottom-to-top.<br>This line should also be horizontal.</div></body></html>