{#- chirp-ui: Grain Overlay
    Film grain texture via SVG noise filter. Pure CSS.

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

        {% call grain() %}
            <img src="photo.jpg" alt="Vintage photo">
        {% end %}

        {% call grain(variant="heavy", animated=true) %}
            <div>Film-like background</div>
        {% end %}
-#}

{% def grain(variant="", animated=false, cls="", attrs="", attrs_map=none) %}
{% set variant_cls = " chirpui-grain--" ~ variant if variant in ("heavy", "subtle") else "" %}
{% set anim_cls = " chirpui-grain--animated" if animated else "" %}
<div class="chirpui-grain{{ variant_cls }}{{ anim_cls }}{{ " " ~ cls if cls else "" }}"
     {{ attrs | html_attrs }}
     {{ attrs_map | html_attrs }}>
    {% slot %}
</div>
{% end %}