I recently switched back to using Firefox instead of Chrome due to Chrome’s unreliability from version to version, and discovered Firefox’s Navigation Bar default font size was smaller than what I was used to seeing with Chrome.
Here’s how you can change the navigation bar’s font size:
To modify the address bar font size, add the following line to the userChrome.css file
#urlbar {font-size: 14pt !important}
If Firefox is running, you’ll need to restart it to pick up the new font size. No doubt you’ll want to experiment with a few different sizes.
And here’s a link to find where your userChrome.css file is.