This is a problem with the font that Firefox uses to display this content and not a language problem. It is possible Firefox uses a corrupted font or a font that isn't available or can't be accessed. You can check for issues like corrupted and duplicate fonts in Font Book. You can right-click and select "Inspect" to open the built-in Inspector with this element selected. *https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/open_the_inspector/ *https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/examine_and_edit_html/ You can check in the <b>Rules</b> tab in the right panel in the Inspector what font-family is used for selected text. You can check in the <b>Fonts</b> 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, if necessary expand "All fonts...". If the Fonts tab is hidden, click the Down arrow at the right end. *https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/edit_fonts/