Untitled

<ul>

  <li>A</li>

  <li>B</li>

  <li>C</li>

  <li>D</li>

  <li>E</li>

  <li>F</li>

  <li>G</li>

</ul>

ul {

  display: flex;

  flex-flow: column wrap;

  list-style: none;

  padding: 0;

  align-content: space-between;

  height: 4em;

}

li {

  border: 1px solid;

}