This could be an issue with a specific font like Helvetica or Arial.

You can right-click and select "Inspect Element" to open the builtin Inspector with this element selected.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/Examine_and_edit_HTML

You can check in the Rules tab in the right panel in the Inspector what font-family is used for selected text. You can check in the Font tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/Edit_fonts

I did as described. Found the font type . But then what? I send a message to Mozilla saying the y is missing and the inspection tool tells me you ( Mozilla) are using Times as the font. And then....... Thank you for the instruction thus far anyway. If I copy the sentence with the issue my computer/firefox suppies the invisible Y in my note to you.

Try the solution in this thread:

• https://support.mozilla.org/en-US/questions/1269532