Avatar for Username

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

Natao arisiva ity resaka mitohy ity. Mametraha fanontaniana azafady raha mila fanampiana.

Add-on dev: How can I edit Firefox UI CSS?

  • 2 valiny
  • 1 manana an'ity olana ity
  • 1 view
  • Valiny farany nomen'i cor-el

dukevin
dukevin
more options

I'm developing an add-on for Firefox which will take the colors from the favicon of the current tab to color bits of the tab-bar dynamically.

I'm having trouble finding out how I can modify browser CSS, for example in the Browser Tool box console, this works perfectly fine: ```const activeTab = document.querySelector('.tabbrowser-tab[selected="true"] .tab-background'); activeTab.style.background = "rgb(0, 221, 255)";```

but when inputting this same code in my add-on, it cannot query that same selector (I've given it tabs and theme permissions). This also does not work as a stylesheet.

Can anyone point me to what I need to access the browser UI DOM?

I'm developing an add-on for Firefox which will take the colors from the favicon of the current tab to color bits of the tab-bar dynamically. I'm having trouble finding out how I can modify browser CSS, for example in the Browser Tool box console, this works perfectly fine: ```const activeTab = document.querySelector('.tabbrowser-tab[selected="true"] .tab-background'); activeTab.style.background = "rgb(0, 221, 255)";``` but when inputting this same code in my add-on, it cannot query that same selector (I've given it tabs and theme permissions). This also does not work as a stylesheet. Can anyone point me to what I need to access the browser UI DOM?

All Replies (2)

Paul
Paul
  • Top 25 Contributor
  • Moderator
more options

Hi

You may wish to ask about this issue in the add-on developers forum at:

https://discourse.mozilla.org/c/add-ons/35

cor-el
cor-el
  • Moderator
  • Top 10 Contributor
more options

Web extensions can't access content in the user interface like the Tab bar, they can only interact with webpage content. You can't do this via an extension, this can only be done via userChrome.css.