How can I remove the rounded corners in Firefox?

Bonjour

A space for users to give product feedback https://support.mozilla.org/en-US/kb/what-mozilla-connect

A old discussion thread https://connect.mozilla.org/t5/discussions/hate-the-rounded-corners-inside-firefox-disabled-them-in-windows/td-p/110499 and a new discussion thread https://connect.mozilla.org/t5/discussions/take-project-nova-for-a-spin-in-nightly/td-p/131273

Thank you very much, this solution was helpful

If you mean the rounded corners around the browser window or tabs, I’d first check whether this appeared after a recent Firefox update. Some UI changes can’t be reverted through the normal settings, so it may depend on exactly which corners you mean. A screenshot would probably make it easier for someone here to point you to the right setting or workaround.