Why won't my website preview load images and layout properly?

[Pigybanc]

Every time I try to preview my website, it has a huge lock on the screen and a blue shopify logo down the bottom.

This happens whether there is a password or not, and even when I enter the password the text seems to load but the images and layout are not working properly.

I have tried multiple different themes, logging in from 4 different browsers across 2 devices and clearing my cache and cookies across all those devices.