The reason I asked about FireFox is because the images, amongst other files that make QuickFile work (including the CSS), are hosted by Microsoft, who had issues with FireFox over the bank holiday (there’s a separate thread on this here).
It has however now been resolved by Microsoft, but may just take some time to update with your browser. Using another browser such as Chrome will fix that.
There’s more information on this in our knowledge base:
If you need any help with any of it, please don’t hesitate to ask 