Style Editor

The Style Editor enables you to:

  • view and edit all the stylesheets associated with a page
  • create new stylesheets from scratch and apply them to the page
  • import existing stylesheets and apply them to the page

To open the Style Editor choose the "Style Editor" option from the "Web Developer" menu (which is a submenu in the "Tools" menu on the Mac). The Toolbox will appear at the bottom of the browser window, with the Style Editor activated:

The Style Editor is divided into two main halves: the style sheet pane on the left, and the editor on the right.

The style sheet pane

The style sheet pane, on the left, lists all the style sheets being used by the current document. You can quickly toggle the use of a given sheet on and off by clicking the eyeball icon to the left of the sheet's name. You can save any changes you've made to the style sheet to your local computer by clicking the Save button in the bottom-right corner of each sheet's entry in the list.

The editor pane

On the right is the editor pane. This is where the source for the selected style sheet is available for you to read and edit. Any changes you make are immediately applied to the page. This makes it easy to experiment with, revise, and test changes. Once you're satisfied with your changes, you can save a copy locally by clicking the Save button on the sheet's entry in the style sheet pane.

The editor provides line numbers and syntax highlighting to help make it easier to read your CSS. It also supports a number of keyboard shortcuts.

The Style Editor automatically de-minimizes style sheets that it detects, without affecting the original. This makes it much easier to work on pages that have been optimized.


Autocomplete is new in Firefox 29.

From Firefox 29 onwards, the Style Editor supports autocomplete. Just start typing, and it will offer you a list of suggestions.

You can switch this off in the Style Editor settings.

Creating and importing style sheets

You can create a new style sheet by clicking the New button in the toolbar. Then you can just start entering CSS into the new editor and watch as the new styles apply in real time just like changes to the other sheets.

You can load a style sheet from disk and apply it to the page by clicking the Import button.

Source map support

CSS source map support is a new feature in Firefox 29.

Web developers often create CSS files using a preprocessor like Sass, Less, or Stylus. These tools generate CSS files from a richer and more expressive syntax. If you do this, being able to see and edit the generated CSS is not so useful, because the code you maintain is the preprocessor syntax, not the generated CSS. So you'd need to edit the generated CSS, then manually work out how to reapply that to the original source.

Source maps enable the tools to map back from the generated CSS to the original syntax, so they can display, and allow you to edit, files in the original syntax. From Firefox 29 onwards, the Style Editor can understand CSS source maps.

This means that if you use, for example, Sass, then the Style Editor will show you, and allow you to edit, Sass files, rather than the CSS that is generated from them:

For this to work, you must:

Viewing original sources

Now, if you check "Show original sources" in the Style Editor settings, the links next to CSS rules in the Rules view will link to the original sources in the Style Editor.

Editing original sources

You can also edit the original sources in the Style Editor and see the results applied to the page immediately. To get this to work there are two extra steps.

First, set up your preprocessor so it watches the original source and automatically regenerates the CSS when the source changes. With Sass you can do this simply by passing the --watch option:

sass index.scss:index.css --sourcemap --watch

Next, save the original source in the Style Editor by clicking the "Save" button next to the file, and saving it over the original file.

Now when you make changes to the source file in the Style Editor the CSS is regenerated and you can see the changes right away.

Keyboard shortcuts

Source editor shortcuts

This table lists the default shortcuts for the source editor.

From Firefox 29, you can choose to use Vim or Emacs key bindings instead. To select these, visit about:config, select the setting devtools.editor.keymap, and assign "vim" or "emacs" to that setting. If you do this, the selected bindings will be used for all the developer tools that use the source editor.

  Windows Mac OS X Linux
Go to line Ctrl + J Cmd + J Ctrl + J
Find in file Ctrl + F Cmd + F Ctrl + F
Find again Ctrl + G Cmd + G Ctrl + G
Select all Ctrl + A Cmd + A Ctrl + A
Cut Ctrl + X Cmd + X Ctrl + X
Copy Ctrl + C Cmd + C Ctrl + C
Paste Ctrl + V Cmd + V Ctrl + V
Undo Ctrl + Z Cmd + Z Ctrl + Z
Redo Ctrl + Shift + Z / Ctrl + Y Cmd + Shift + Z / Cmd + Y Ctrl + Shift + Z / Ctrl + Y
Indent Tab Tab Tab
Unindent Shift + Tab Shift + Tab Shift + Tab
Move line(s) up Alt + Up Alt + Up Alt + Up
Move line(s) down Alt + Down Alt + Down Alt + Down
Comment/uncomment line(s) Ctrl + / Cmd + / Ctrl + /


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117193 bytes 2014-02-06 23:27:24 wbamberg
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Last updated by: lorchard_mozilla,