baseline-source CSS property

/* Keyword values */
baseline-source: auto;
baseline-source: first;
baseline-source: last;

/* Global values */
baseline-source: inherit;
baseline-source: initial;
baseline-source: revert;
baseline-source: revert-layer;
baseline-source: unset;

<span>Baseline ___</span>

<span class="box first">
  <span>First</span>
  <span>A</span>
  <span>B</span>
  <span>C</span>
</span>

<span class="box auto">
  <span>Auto</span>
  <span>A</span>
  <span>B</span>
  <span>C</span>
</span>

<span class="box last">
  <span>A</span>
  <span>B</span>
  <span>C</span>
  <span>Last</span>
</span>

body {
  font-family: sans-serif;
}

.box {
  border: 2px solid #888888;
  width: 50px;
}

span {
  padding: 0.4rem;
}

.box {
  display: inline-flex;
  flex-direction: column;
}

.first {
  baseline-source: first;
}

.auto {
  baseline-source: auto;
}

.last {
  baseline-source: last;
}