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

The all-new Inspector panel in Firefox 57.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:

This is the button in Firefox 57 Inspector you can use to select elements on a web page.

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.

HTML pane

The Inspector is split into two halves. The left-hand half is occupied by the HTML pane:

These are the tasty new HTML and CSS panes in Firefox 57.

To learn more about the structure of the HTML pane, see the guide to examining and editing HTML.

CSS pane

The right-hand side of the Inspector is occupied by the CSS pane:

The rules view within the Inspector.The CSS pane is divided into 5 views:

  • Rules view
  • Computed view
  • Layout view
  • Animations view
  • Fonts view

Use the tabs along the top to switch between the different views.

Note: From Firefox 62 onwards, you can split the Rules view out into its own pane, separate from the other tabs on the CSS pane — this is called 3-pane mode.

Rules view

The Rules view lists all the rules that apply to the selected element, ordered from most-specific to least-specific. See above.

See Examine and edit CSS for more details.

Computed view

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:

The Computed view within the Inspector.

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.

Fonts view

The Fonts view shows all the fonts in the page along with editable samples.

The all-new Inspector panel in Firefox 57.

See View fonts for more details.

Animations view

The Animations view gives you details of any animations applied to the selected element, and a controller to pause them:


This is the Animations pane in the Firefox 57 Inspector.

See Work with animations for more details.

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Last updated by: irenesmith,