foldergallery.html

<style>
  div.gallery {
     display: flex;
     flex-wrap: wrap;
  }
        div.gallery a {
            flex-grow: 1;
            object-fit: cover;
            margin: 2px;
            display: flex;
        }

        div.gallery a img {            
            height: 200px;
            object-fit: cover;
            flex-grow: 1;
        }

    </style>

    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/fancybox/3.4.0/jquery.fancybox.min.css" />

    <div class="gallery">
        {{ $base := .Get "src" }}
	{{ $path := print "static/" (.Get "src") }}

	{{ range (readDir $path) }}
        {{- $thumbext := "-thumb" }}
        {{- $isthumb := .Name | findRE ($thumbext | printf "%s\\.") }}<!-- is the current file a thumbnail image? -->
        {{- $isimg := lower .Name | findRE "\\.(gif|jpg|jpeg|tiff|png|bmp)" }}<!-- is the current file an image? -->
        {{- if and $isimg (not $isthumb) }}
        {{- $thumb := .Name | replaceRE "(\\.)" ($thumbext | printf "%s.") }}
            <a data-fancybox="gallery" href="/{{ $base }}/{{ .Name }}">
                <img src="/{{ $base  }}/{{ $thumb }}">  <br/>            
            </a>
        {{- end }}
	{{ end }}
    </div>