This article is a quick tour of the main sections of the Page Inspector's user interface.
It covers the three top-level components of the Inspector's UI:
- the "Select element" button
- the HTML pane
- the CSS pane
This guide is intentionally kept as short as possible. It links to various how to guides for the details of how to work with the Inspector.
Select element button
The Inspector gives you detailed information about the currently selected element. The Select element button is one way you can select an element for inspection:
Note that it's actually part of the main toolbox toolbar, so it's immediately accessible from any tool, not just the Inspector.
To learn how to select an element, see the guide to selecting an element.
The Inspector is split into two halves. The left-hand half is occupied by the HTML pane:
To learn more about the structure of the HTML pane, see the guide to examining and editing HTML.
The right-hand side of the Inspector is occupied by the CSS pane:
The CSS pane is divided into 4 views:
- Rules view
- Computed view
- Fonts view
- Animations view
Use the tabs along the top to switch between the different views.
The Rules view lists all the rules that apply to the selected element, ordered from most-specific to least-specific:
See Examine and edit CSS for more details.
The Computed view shows you the complete computed CSS for the selected element, and an editable visual representation of the box model for the element:
To learn more about the box model view, see Examine and edit the box model. Note that before Firefox 50, the box model view did not appear in the "Computed view" tab, but had its own tab.
To learn more about the CSS declarations listed in this view, see Examine computed CSS.
In Firefox 47 only, the Fonts view is disabled by default. If you want to see the Fonts view in Firefox 47, visit
about:config, find the preference
devtools.fontinspector.enabled, and set it to
Before and after Firefox 47, the Fonts view is enabled by default.
The Fonts view shows all the fonts in the page along with editable samples.
See View fonts for more details.
The Animations view gives you details of any animations applied to the selected element, and a controller to pause them:
See Work with animations for more details.
Show/hide CSS pane
From Firefox 40 onwards, there's a button in the toolbar that you can use to show or hide the CSS pane: