Nested Attribute Tags

Slots can contain slots. An attribute tag may hold its own attribute tags, and the nesting mirrors straight into input:

<my-tag>
  <@a value=1>
    <@b value=2/>
  </@a>
</my-tag>

gives my-tag an input of { a: { value: 1, b: { value: 2 } } } — @b becomes a property of @a, not a sibling. Combine that with repetition and you can describe genuinely structured content: a plan containing its features, a section containing its links, a table row containing its cells — each level just an iterable property of the one above.

<pricing-table>
  <@plan name="Hobby" price=9>
    <@feature>Unlimited projects</@feature>
    <@feature>Community support</@feature>
  </@plan>
  <@plan name="Pro" price=29>
    <@feature>Everything in Hobby</@feature>
    <@feature>Priority support</@feature>
  </@plan>
</pricing-table>

Consuming nests the loops: <for|plan| of=input.plan> outside, <for|feature| of=plan.feature> inside — repetition-by-iterable at both depths, exactly the protocol from the repeated-slots lesson.

The page on the right already describes its plans in that nested shape; pricing-table.marko renders the plans but ignores each plan’s features:

1. Inside the plan loop, where the TODO sits, add the inner loop: <for|feature| of=plan.feature> rendering <li><${feature.content}/></li>.
2. Two plans, two feature lists, one declarative call site — structure described where it’s used, rendered where it’s owned.