Hugo-theme-stack/layouts/partials/article-list/default.html

<article class="{{ if .Params.image }}has-image{{ end }}">
    {{ $image := partial "helper/image" . }}

    {{ if $image.exists }}
        <div class="article-image">
            <a href="{{ .Permalink }}">
                {{ if $image.local }}
                    {{- $thumbnail := $image.src.Fill "800x250" -}}
                    {{- $thumbnailRetina := $image.src.Fill "1600x500" -}}

                    <img src="{{ $thumbnail.RelPermalink }}" 
                        srcset="{{ $thumbnail.RelPermalink }} 1x, {{ $thumbnailRetina.RelPermalink }} 2x"
                        width="{{ $thumbnail.Width }}" height="{{ $thumbnail.Height }}" loading="lazy"
                        alt="Featured image of post {{ .Title }}" />
                {{ else }}
                    <img src="{{ $image.src }}" loading="lazy" alt="Featured image of post {{ .Title }}" />
                {{ end }}
            </a>
        </div>
    {{ end }}

    {{ partial "article/components/details" . }}
</article>