Marks in checkboxes invisible
On web pages that have checkboxes, I can't see checkmarks in the boxes, even after I've checked them.
When I click inside the checkboxes, the white checkmark is visible for as long as I hold down the mouse key. As soon as I let it go, the checkmark becomes invisible and the checkbox looks exactly the same way it looked before I checked it.
Opaite Mbohovái (1)
Make sure you use a GTK 3 theme in your Linux distribution. Such issues can happen if a GTK 2 theme is used.
If you use a custom theme in Firefox and not a builtin theme then try one of the builtin themes. "3-bar" menu button or Tools -> Add-ons -> Appearance