Here, we will see, how you can set the thumbnail of fotorama slider in product view page to left as vertical in Magento 2.
Magento uses the view.xml file for gallery and magnifier theme settings.
For example, if you are using the default theme luma, you should find the view.xml at vendor/magento/theme-frontend-luma/etc/view.xml.
In this file, we can see a variable navdir under <var name=”gallery”> node.
This variable has the ability to change the thumbnails alignment in Fotorama.
<var name="navdir"> horizontal</var>
To set the thumbnails as vertical, you need to change the code as below:
<var name="navdir"> vertical</var>
You can define your own custom view.xml file in your theme at app/design/frontend/THEME-VENDOR/THEME/etc/view.xml, and change navdir as per your requirement.