#let poem(content) = {
  set par(first-line-indent: 0em)

  align(center, block[
    #set align(left)
    #set block(breakable: false)
    #emph(content)
  ])
}

#poem[
  #block[
    'Twas brillig, and the slithy toves \
    #h(1em)Did gyre and gimble in the wabe; \
    All mimsy were the borogoves, \
    #h(2em)And the mome raths outgrabe.
  ]
]