This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Purpose of the "@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */" css code?

  • 5 iimpendulo
  • 1 inayo le ngxaki
  • 50 views
  • Impendulo yokugqibela ngu Rick W

more options

Can anyone please explain the purpose of the

   @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */ 

css code, which is often recommended to head any userchrome.css text inside the chrome folder? What happens when you omit this @namespace url line?

Can anyone please explain the purpose of the @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */ css code, which is often recommended to head any userchrome.css text inside the chrome folder? What happens when you omit this @namespace url line?

Isisombulu esikhethiweyo

Hi, have a read of https://www.userchrome.org/adding-style-recipes-userchrome-css.html

If your question is resolved by this or another answer, please take a minute to let us know. Thank you!

Funda le mpendulo kwimeko leyo 👍 1

All Replies (5)

more options

Is it simply an advertisement for Firefox XML User Interface Language?

more options

You use this line to set the namespace for the code on that page.

more options

Why does one need to set a namespace?? What happens if it is not done?

more options

Isisombululo esiKhethiweyo

Hi, have a read of https://www.userchrome.org/adding-style-recipes-userchrome-css.html

If your question is resolved by this or another answer, please take a minute to let us know. Thank you!

more options

Thanks, Scribe, that is very useful:

Scribe said

Hi, have a read of https://www.userchrome.org/adding-style-recipes-userchrome-css.html

Good to know it is safe to leave that namespace line out of my userchrome.css code.