You could attached the screenshot to a reply. I assume it doesn't show any sensitive information.

https://support.mozilla.org/questions/1182406#question-reply

Does zoom help (hold down Ctrl and tap the + key a few times)? If only one field is small, that may create other issues...

Well, you are right, I was able to attach the file as a reply.

No the zoom does not help. Perhaps if you see the screen shot you will be able to suggest a solution.

Thanks for your help.

"One of these things is not like the others."

Does the field allow you to type any non-numeric digits, whether periods or letters? If those are blocked, it could be one of the new "number" fields that is a recently enabled kind of control. Possibly their style sheet doesn't handle those, so you see it in its unfortunately small default size. (Based on your operating-system level settings.)

To see what kind of field it is, you could use the Inspector tool. Right-click the field and choose Inspect Element. A panel should open in the lower part of the tab and after various preparations, you should see that element highlighted in blue in the midst of the page's HTML structure.

A standard text input is <input type="text">. Is that one an <input type="number">? If it's text, I don't know why it looks different than the others.

Otherwise, do you want to try "the usual"? If a site is generally known to work in Firefox, these are general suggestions to try when it stops working normally:

Cache and Cookies: When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes. If you do not see the number going down on the page, you can reload it using Ctrl+r to check progress.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button

In the dialog that opens, the current site should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually.

Then try reloading the page. Does that help?

Testing in Firefox's Safe Mode: In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, userChrome.css/userContent.css, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

Thanks so much. I did every thing you suggested, except the Safe Mode. The elements all read "text" and I cleared the cache & cookies, closed it all & reloaded the page. No change. I am not sure I know enough to do the safe mode troubleshoot. What I don't truly understand is why it just suddenly happened. I am sending a screen shot of Chrome where it is not doing this. I have 2 monitors on my desk and need to use 2 browsers to do different things. Should I have to start using Chrome for this side of the work, then what browser can I use for receiving all the google emails and that side of the work. Firefox never did work well on that side of the work, when I send orders to a shipper at night, it won't copy & paste right. Any suggestions

For Safe Mode, you can just start Firefox in its safe mode, visit the site, and check for any difference. To return to normal, exit Firefox, and then start it up normally.

If the field is normal in Firefox's Safe Mode, check your extensions. You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any system extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything that looks like it relates to forms or privacy of sensitive data? If in doubt, disable.

Sometimes a link will appear above a disabled extension to restart Firefox before the change takes effect. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

WOW, you are a good teacher. I did the safe mode, disabled everything, Still have the problem. Then I followed all the links about safe mode, except for uninstalling and reinstalling. UGH. I still have the problem. I only had 3 extensions & 2 said they were added by Firefox, & one was a flash player, so I updated it and restarted in safe mode anyway. Still had the problem & now that I restarted, the problem is still there. I am definitely learning more than I wanted to. lol Since it is only happening on the Firefox browser, I don't think I want to pay the tech guys to trouble shoot it in the Magento program. (they will laugh at me). If you can think of anything else, let me know. I did see that Firefox is coming out with a new "faster" version later this month. Maybe if I upgrade to that one, it will fix it? Do you think that is possible?

Hmm, I'm a little worried that a sensitive data field is behaving oddly for no apparent reason.

Can you tell whether the field is using a different font from other fields? Different fonts may have different metrics which affect the size of the field. Digits often look the same in different fonts, so that may be difficult to spot.

Do you still have an Old Firefox Data folder on your desktop from the Firefox Refresh? It might be interesting to compare the prefs.js file in that folder with the one in your live profile, to see whether any font-related preferences are different between the two. However, I don't know whether that is worth the effort at this point.

Firefox 57 might make some changes that affect the page, but I can't think of any dramatic ones off the top of my head; most of the changes are under the covers and in the user interface area.

If you want to test a pre-release build of Firefox 57, you can use the PortableApps version. It installs into a separate folder and doesn't share data with your main installation of Firefox, so it's easy to try and delete.

https://portableapps.com/apps/internet/firefox_portable/test

I do have the Old Firefox Data folder on my desktop. I opened it and looked at the prefs.js file, but it didn't tell me anything.

What do you think would happen if I do a windows restore back before the firefox was refresed? Do you think it would delete the new stuff & go back to the old one.  ???

Can you right-click this credit card number input field and select Inspector in the drop-down menu list?

That will open the builtin Inspector in a panel at the bottom of the Firefox window. Please provide a screenshot that shows this Inspector panel like jscher wrote above.

• https://developer.mozilla.org/en/Tools/Page_Inspector

OK, I did a screenshot in inspector. Let me know if you figure anything out. I really appreciate all the help.

On the right side of the Inspector, where you see Rules, Computed... there is a little triangle to change to the Fonts panel. If you show that panel and click the difference controls, maybe you can see some difference among them?

ok, I have tried everything you suggested. I don't know if windows restore will help, but after work tonight I am going to try it.

If that does not work, I am going to uninstall Firefox & reinstall it. If that does not work, I guess I will be using Chrome & Internet Explorer. UGH.

Thank you so much for all your help.