Can you give an example?

You may have zoomed the page(s) by accident.
Reset the page zoom on pages that cause problems.

• View > Zoom > Reset (Ctrl/Command+0 (zero))

• http://kb.mozillazine.org/Zoom_text_of_web_pages

If you have made changes to Advanced font settings like increasing the minimum/default font size then try the default minimum setting "none" and the default font size 16 in case the current setting is causing problems.

• Tools > Options > Content Fonts & Colors > Advanced > Minimum Font Size (none)

Make sure that you allow pages to choose their own fonts.

• Tools > Options > Content Fonts & Colors > Advanced: [X] "Allow pages to choose their own fonts, instead of my selections above"

It is better not to increase the minimum font size, but to use an extension to set the default page zoom to prevent issues with text not being displayed properly.

You can try these steps in case of issues with web pages:

You can reload web page(s) and bypass the cache to refresh possibly outdated or corrupted files.

• Hold down the Shift key and left-click the Reload button
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (Mac)

Clear the cache and cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I posted some screencaps. One image shows the page as displayed in Firefox and the other similar image shows the same page in IE.

I tried all of the possible solutions in Cor-el's response post but I am still having the same issue. I reset the zoom, checked the font size settings, cleared the cache, deleted the cookies and so far nothing has worked.

You may have one of these:

(1) Large minimum font size

A "minimum" font size is designed to prevent unreadable tiny print, but sizes above 9 or 10 can cause layout distortions.

You can check for this issue in the Options dialog:

"3-bar" menu button (or Tools menu) > Options > Content

Click the "Advanced" button. You can have a minimum font size set for a variety of different languages, so use the selector at the top to check these common ones:

• Western
• Other Languages

(2) Text-only zoom

Firefox has the options of full zoom or text-only zoom. Full zoom preserves proportionality and layout, but text-only zoom can make the text larger than the allotted space.

This is a little harder to edit. If you do not display the classic menu bar normally, tap the Alt key or press F10 to display it temporarily. Then:

View menu > Zoom > uncheck Zoom Text Only

Any luck?

What is the current minimum font setting?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes