index.php

<div class="sample">
  <?php if ($hoge === true):?>
  <div class="inner">
    <p>
      hogehoge
    </p>
    <p>
      <?php echo $hoge;?>
    </p>
  </div>
  <?php else:?>
  <p>
    fugafuga
  </p>
  <?php endif;?>
</div>

index.php.slim

.sample
  <?php if ($hoge === true):?>
    .inner
      p hogehoge
      p <?php echo $hoge;?>
  <?php else:?>
      p fugafuga
  <?php endif;?>