Pretend to set a custom baseline to a flexbox

HTML

<div class="container underline">
    <div class="element">
        <div>C</div>
    </div>
</div>

CSS

.container {
  display:flex
}

.element {
  padding: 1em;
  width: 200px;
  text-align: center;
}

.overline {
    align-items: flex-end;
}

.underline {
    align-items: flex-start;
}