body {
  margin: 0;
  padding: 0;
  width: 6em;
}

body > ol {
  margin: 0;
  padding: 0;
}

body > ol > li {
  display: block
}

body > ol > li > span {
  display: block;
  border-right: .1em solid;
  border-bottom: .1em solid;
}

body > ol > li > div {
  display: none;
  position: absolute;
  padding: .2em;
  top: 0;
  right: 0;
  bottom: 0;
  left: 3em; /* must be 1/2 width of body due to increased font-size */
  font-size: 2em;
}

body > ol > li:hover > div {
  display: block;
}