;
      height: 1em;
      position: absolute;
      top: auto;
    }

/*
"
Layout calculation rules (such as those in CSS2.1, Section 10.3) that apply to the horizontal dimension in horizontal writing modes instead apply to the vertical dimension in vertical writing modes.
"
7.1 Principles of Layout in Vertical Writing Modes
http://www.w3.org/TR/css-writing-modes-3/#vertical-layout

So here, *-top and *-bottom properties are input into the §10.3.7 algorithms where *-top properties refer to *-left properti