Tiny image thumbnails on single product page

In some cases you may encounter the problem of small image thumbnails on single product page of Chromium theme. The problems looks like this:
As you can see, the thumbnails on the image are tiny.

To fix the problem you need to add the following css code to Appearance -> Customize -> Additional CSS section of your site:

/* Small img thumbnails fix */
@media screen and (min-width: 768px) {
.product-classic-style .product-images-wrapper .flex-control-thumbs {
width: 100% !important;
}
}

This should resolve the tiny thumbnail problem on your site.