1. A concise explanation of the problem you're experiencing.
The navigation buttons are not visible when Cesium 3D is opened in Fireforx whereas in chrome the buttons are visible.
We have a <base> tag in the landing page where absolute is url is provided.
If we remove base tag then the icons are visible but we dont want to remove it as we have many relative urls which are dependent on the <base> tag absolute url.
2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.
3. Context. Why do you need to do this? We might know a better way to accomplish your goal.
4. The Cesium version you're using, your operating system and browser.