URL: https://mmlm-shop.mystagingwebsite.com/products/family-portrait-2-family-members/

Browser / Version: Firefox Mobile (Tablet) 59.0
Operating System: Android 4.4.2
Tested Another Browser: Yes

Problem type: Design is broken
Description: The modals that appears first and the ones popped up after clicking black characters, are flickering when scroll down or up
Steps to Reproduce:

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