<div
style="height: 14px;
color:white; background:white;
position:absolute; left:77px; top:8px;
transform:rotate(27deg);
-ms-transform:rotate(27deg); /* IE 9 */
-webkit-transform:rotate(27deg); /* Safari and Chrome */
width:1px"/>
And here's a general-purpose kit for drawing lines a lot, which provided the clues I needed:
http://monkeyandcrow.com/blog/drawing_lines_with_css3/
So now you know.