[Jellby]

You can use plain <div>, with something like:

<div class="poetry">
  <div class="stanza">
    <div>line 1</div>
    <div>line 2</div>
    <div>line 3</div>
  </div>
  <div class="stanza">
    <div>line 4</div>
    <div>line 5</div>
    <div>line 6</div>
  </div>
</div>

div.poetry { /* set margins for the whole poetry block */ }
div.stanza { /* set margins for each stanza */ }
div.poetry div { /* set hanging indent for poetry lines */ }