hugo-theme-stack/layouts/_markup/render-image.html

{{- $image := partial "helper/image" (dict "Resources" .Page.Resources "Image" .Destination) -}}
{{- $alt := .PlainText | safeHTML -}}

{{/* SVG and external images won't work with gallery layout, because their width and height attributes are unknown */}}
{{- $galleryImage := and $image.Height $image.Width -}}

<img src="{{ $image.Permalink }}"
	{{ with $image.Width }}width="{{ . }}"{{ end }}
	{{ with $image.Height }}height="{{ . }}"{{ end }}
	loading="lazy"
	{{ with $alt }}
		alt="{{ . }}"
	{{ end }}
	{{ if $galleryImage }}
		class="gallery-image" 
		data-flex-grow="{{ div (mul $image.Width 100) $image.Height }}"
		data-flex-basis="{{ div (mul $image.Width 240) $image.Height }}px"
	{{ end }}
>