{#- chirp-ui: Site Shell component
    Full-page scroll shell with sticky header, main content, and footer.
    The scrolling-page equivalent of app_shell — use for marketing sites,
    landing pages, docs homes, and any layout that scrolls the whole page.

    Manages stacking context so child z-indices in content never bleed
    over the sticky header. Apps using site_shell never need to think
    about isolation: isolate or z-index on the main content area.

    Named slots: header (sticky top region), default (page content), footer.

    Usage:
        from "chirpui/site_shell.html" import site_shell

        call site_shell(ambient=true)
            {% slot header %}site_header(...){% end %}
            Page content here
            {% slot footer %}site_footer(...){% end %}
        end
-#}

{% def site_shell(ambient=false, cls="") %}
<div class="chirpui-site-shell{{ " chirpui-ambient-root" if ambient else "" }}{{ " " ~ cls if cls else "" }}">
    {% if ambient %}<div class="chirpui-ambient" aria-hidden="true"></div>{% end %}
    {% slot header %}
    <div class="chirpui-site-shell__main">
        {% slot %}
    </div>
    {% slot footer %}
</div>
{% end %}