Screen shot of the error?

By default, Firefox follows your Windows "Text Size" setting. On laptops, that's often 125%. On desktop systems, it may be 100%. But Firefox also lets you override this and specify your own scaling factor. This will scale up both the text and the icons in the toolbar area, and in web pages. Here's how to give it a try: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk. (2) In the search box above the list, type or paste '''devp''' and pause while the list is filtered (3) Double-click the '''layout.css.devPixelsPerPx''' preference and enter '''1.5''' and click OK. This is equivalent to setting the "Text Size" in Windows 10 to 150%. What do you think, is this the same, better, too large? You can experiment with this setting. Please do not go lower than 1 or higher than 3. If things get out of control, you can right-click the setting and choose Reset, which is the bottom item on the right-click context menu. Can you find a size that works well overall?