How can I access .Site inside a Shortcode?

For an image gallery I created this shortcode:

<figure>
    <a href="{{ .Site.Param.ImageBase }}/{{ .Get "href" }}" data-size="{{ .Get "size" }}">
     ...
</figure>

.Site.Params.ImageBase is rendered as Zgotmlpz . (How) Can I pass a parameter to a shortcode?

@frank

This should help you:
https://hugodocs.info/functions/safehtmlattr/