Steps to replicate...

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/

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 Fonts 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://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/edit_fonts/

Please check this. when i change the font-family from var(--base-font-family) to any font name like arial then its work.

Searching the Style editor shows: --base-font-family:Inter,X-LocaleSpecific,sans-serif; The Inter font is downloaded from the server.

What font is Firefox using in your case ?

You can check in the Fonts 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. You may have to click the down arrow to reveal Fonts.

• https://firefox-source-docs.mozilla.org/devtools-user/page_inspector/how_to/edit_fonts/