{#- chirp-ui: Band component
    Full-bleed marketing section panel with optional pattern overlay.

    Width variants control breakout behavior:
      inset     — rounded panel, slightly wider than container (default)
      bleed     — viewport-wide background, content contained
      contained — no breakout, same width as parent

    Surface variants: default, elevated, accent, glass, gradient.
    Patterns: dots-sm, dots-md, grid, crosshatch, diag (existing chirpui-band--pattern-* CSS).

    Named slots: header (e.g. section_header), default (content).

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

        call band(variant="elevated", width="inset", pattern="grid")
            {% slot header %}section_header("Featured"){% end %}
            grid(cols=3) ...cards... end
        end

        call band(width="bleed", variant="accent")
            Full-bleed accent section content.
        end
-#}

{% def band(variant="", width="inset", pattern="", cls="") %}
{% set variant = variant | validate_variant(("default","elevated","accent","glass","gradient"), "default") %}
{% set width = width | validate_variant(("inset","bleed","contained"), "inset") %}
{% set _cls = [c for c in [
    "chirpui-band",
    "chirpui-band--" ~ width,
    "chirpui-band--" ~ variant if variant != "default" else "",
    "chirpui-band--pattern-" ~ pattern if pattern else "",
    cls
] if c] %}
<section class="{{ _cls | join(' ') }}">
    {% slot header %}
    {% slot %}
</section>
{% end %}