Since installing Mojave I don't get any checkboxes in Chrome or Opera - they are in the DOM, but don't show up in the UI - Safari and Firefox work fine.
It seems that changing the zoom on a page with checkboxes using ⌘+- and ⌘++ make the checkboxes visible. They only do not appear when the page is at 100% zoom. The top image is at 100%, and the bottom (with the checkbox visible) is at 90%.
It seems that changing the zoom on a page with checkboxes using ⌘+- and ⌘++ make the checkboxes visible. They only do not appear when the page is at 100% zoom. The top image is at 100%, and the bottom (with the checkbox visible) is at 90%.