Checkbox status on/off almost indistinguishable

[GeoBeBee]

Hi, I'm using a Raspberry Pi 3 with the supplied Epiphany Web Browser, and the Domoticz check boxes almost look the same irrespective of whether they are checked or not. They just look very slightly darker at the top or bottom. I'm wondering how I can change them to something more obvious? I'd also be interested to know if others have had this problem with checkboxes on the Raspberry Pi (I can't find anything referring to it on this forum)? Thanks
ps. I tried all of the themes, the browser cache was updated, but I didn't notice much difference....