e="width: 4em">
    楽しいドライブ。</div>
  <!-- Only one character can fit to `1em`, but no break before the period. -->
  <div style="width: 1em">
    楽しいドライブ。</div>
  <!-- Breaks even before the period if `overflow-wrap`. -->
  <div style="width: 1em; overflow-wrap: anywhere">
    楽しいドライブ。</div>
</div>
