How do I change the thumbnail size of a fotorama slider?

I've been using the Fotorama plugin to create a slider on my website. It works as it should, but I want to change the size of the thumbnails that are shown, and I can't figure out how. The website is: http://jeannebard.ch/?p=123.

Solution

See the full list of options for fotorama here: http://fotorama.io/customize/options/

Options can be passed via data attributes:

<div class="fotorama"
     data-thumbwidth="120"
     data-thumbheight="120">
  <img src="1.jpg">
  <img src="2.jpg">
</div>

...or JavaScript:

$('.fotorama').fotorama({
  thumbwidth: '120',
  thumbheight: '120'
});

...or the Shortcode if using the plugin version:

[gallery ids="1,2,3" nav="thumbs" thumbwidth="120" thumbheight="120"]

This example would set the thumbnails twice their current size, to 120x120.