templates/tree_block.html

<details class="tree-item ml-3 mt-1.5 border-l-2 border-dashed border-white/10 pl-3 [&[open]]:border-l-indigo-500/40">
  <summary class="tree-summary cursor-pointer select-none rounded-md px-3 py-1.5 text-sm font-semibold text-pink-400 transition-all hover:bg-white/5">{header}</summary>
  <div class="py-1">{content}</div>
</details>