If i understand right , you want to know how to creat new element, a new line of css, you can do this only clicking on the line above that line where you will insert the new element, press the right arrow until the a new line be created

See also:

• Web Console
• Videos

This is what im trying to do: https://dl.dropboxusercontent.com/u/345640/firefoxelement.mov

For some reason i cant seem to find this function in firefox

I get a 404 for the video.

I don't think Firefox's dev tools let you create new elements in the DOM, even in the Inspector pane, which is a more likely location than the Style editor.

When I need to do that I use the DOM Inspector extension: https://addons.mozilla.org/en-US/firefox/addon/dom-inspector-6622/

Video was still uploading is done now

Open the Dev Tool, in the Header click in Style Editor.

Why my image annex dont appear? https://support.cdn.mozilla.net/media.../2014-01-03-16-03-09-797367.png

Dont have a button to add a new element but if you click on the somewhere in the page you will can edit, add, remove style!

This video you can see someone editing the style of the page

I don't see a way to add a new selector for the current element to the Style Editor in Firefox 26 dev tools.

In the Inspector tool in Firefox 26 with the Rules pane displayed to the right, I don't see a way to add a new selector for the current element in the Rules pane.

In the Style Editor tool in Firefox 26, I can write a new rule in any of the available contexts, but I would need to copy the selector from the Inspector view first (e.g., right-click the element and choose Copy Unique Selector) or type a general one, whichever is applicable.