<!DOCTYPE html>
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
<style>
.flex {
  display: flex;
  align-items: baseline;
  font: 25px/1 Ahem;
}
</style>

<body>
<div class="flex">
  <span>XX</span>
  <div><div>YY</div></div>
</div>
</body>