Li items not centered in Ol element containing box

Question

Im having trouble understanding how to to vertically center the menu "li" items within the green section("ol" element). I tried to set margin top & bottom to "auto" but with no effect.

here is the CSS:

.red-box {
  background-color: red;
  height: 100px;
}

ol {
  background-color: green;
  text-align: center;
  height: 25px;
}

li {
  display: inline-block;
}