ImageGallery-omeka-module/view/common/block-layout/imageGallery.phtml

<?php
$this->headLink()->appendStylesheet($this->assetUrl('css/gallery.css', 'ImageGallery'));
?>

<?php $image_id = 0; ?>


<div class="archive-gallery">
	<div class="source-link">
		<a href="">Source</a>
	</div>

	<section id="<?= $gallery_id ?>"
					 class="gallery"
					 style="padding-top: 400px; max-width: <?= $max_width ?>%;">

	<?php foreach ($images as $image) { ?>
		<?php $image_id = $image_id +1;
					$img_id = $gallery_id . '-' . $image_id;
		?>
	  <div class="gallery__item">
	    <input type="radio"
						 id="<?= $img_id ?>"
						 checked name="gallery"
						 class="gallery__selector"/>
	    <img class="gallery__img"
					 style=""
					 src="<?= $image['media_url'] ?>"
					 item_url="<?= $image['item_url'] ?>"
					 alt=""
			/>
	    <label for="<?= $img_id ?>" class="gallery__thumb">
				<img src="<?= $image['media_url'] ?>"
						 alt=""
						 item_url="<?= $image['item_url'] ?>"
						 onclick="updateSourceURL(this)"
				/>
			</label>
	  </div>

	<?php } ?>

	</section>

	<?php if ($title) { ?>
	<div class="item_title">
		<?= $title ?>
	</div>
	<?php } ?>

</div>


<script>

function updateSourceURL(thumbnail){
	$(thumbnail).closest(".archive-gallery")
							.find('.source-link')
							.find('a').prop('href', $(thumbnail).attr('item_url'));
}
jQuery(document).ready(function() {
	$('.archive-gallery').each(function(i, el){
		var first_thumbnail = $(el).find('.gallery__img:first')
		updateSourceURL(first_thumbnail)
	});
});

jQuery(document).ready(function() {
	var gallery_image_height=0;
	$( ".gallery__img" ).each(function( index ) {
		if ($(this).height() > gallery_image_height) {
			gallery_image_height = $(this).height();
		}
	});
	$( ".gallery__img" ).each(function( index ) {
		$(this).css('height', gallery_image_height)
	});
	$('section.gallery').css('padding-top', gallery_image_height)
});

</script>