I just tried on Safari and Firefox without this issue. I suspect you might have a plugin that is modifying CSS on the page. You would be surprised how many plugins do this (including ad blockers). I would try a fresh instance of the browser to rule out those kinds of issues. Seeing as I cannot reproduce it I would need something more than just the parsing log from Firefox.
For example, in the web tools you will see a tab on the top right labeled “Styles”. With the div containing the text selected, you will be able to see which CSS properties are being applied to that element. Therefore, you should be able to find what is making the text white in this instance. If you can maybe find this or attach screenshots, that would be helpful. Please note the elements will inherit the properties from their parent elements if they are not explicitly defined which means you will have to traverse outward until you find the class causing the issue.