UI Tour

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 or three sections, depending on your settings. You can toggle the 3-pane view of the Inspector. The following image shows the 2-pane layout:

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

In 2-pane mode, the Inspector includes the HTML Pane, and the CSS Pane, which can contain one of six tools:

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

The following image shows the 3-pane mode (available from Firefox 62 onwards) which moves the CSS Rules view into a separate pane in the center of the Inspector. The following image shows 3-pane mode:

As you can see, the CSS pane has moved into the center of the Inspector. To learn more about the structure of the HTML pane, see the guide to examining and editing HTML.

Rules view

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

The rules view within the Inspector.

See Examine and edit CSS for more details.

Layout view

The Layout view displays the box model of the page. If the page includes any sections using either the Flexbox display model or CSS Grids, this view shows the Flexbox or Grid settings used on the page.

To learn more about the Layout 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.

Computed view

The Computed view shows you the complete computed CSS for the selected element:

The Computed view within the Inspector.

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.

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.