neon-harvest/layouts/partials/image.html

<img class="{{ .class }}"
	{{- with .image -}}

        {{ $smallest := (.Resize "320x webp q60") }}

		srcset="
    		{{- with $smallest -}}
        		{{ printf "%s %dw," .RelPermalink .Width }}
    		{{- end -}}

    		{{- with (.Resize "480x webp q60") -}}
        		{{ printf "%s %dw," .RelPermalink .Width }}
    		{{- end -}}

    		{{- with (.Resize "600x webp q70") -}}
        		{{ printf "%s %dw," .RelPermalink .Width }}
    		{{- end -}}

    		{{- with (.Resize "800x webp q90") -}}
        		{{ printf "%s %dw," .RelPermalink .Width }}
    		{{- end -}}

		"

		sizes="
    		(max-width: 480px) 320px;
    		(max-width: 600px) 480px;
    		(max-width: 800px) 600px;
    		800px"

    	src="
    	{{- with $smallest -}}
    		{{ .RelPermalink }}
    	{{- end -}}"

        alt="{{ .Params.alt }}"
	{{- end -}}
>