Get started viewing and changing CSS

發行項
12/07/2023

To learn the basics of using DevTools to view and change the CSS for a page, follow the interactive tutorial sections in this article.

View the CSS for an element

Open the CSS Examples demo page in a new window or tab. (To open a link in a new window or tab, right-click the link. Or, press and hold Ctrl (for Windows, Linux) or Command (for macOS) and then click the link.)
Right-click the Inspect Me! text, and then select Inspect.

In the DOM Tree panel under the Elements tool, the Inspect Me! element is highlighted:
In the Inspect Me! element, find the value of the data-message attribute and copy it.
On the page view, enter the data-message value that you copied in the Value of data-message text box.
Right-click the Inspect Me! text, and then select Inspect.
In DevTools, on the Elements tool, select the Styles panel. The Inspect Me! element is highlighted in the Styles panel.
In the Inspect Me! element, find the aloha class rule. This rule is displayed, because it's being applied to the Inspect Me! element.
In the aloha class, find the value for the padding style and copy it:
On the page view, paste the padding value in the Value of padding text box.

Add a CSS declaration to an element

Use the Styles panel when you want to change or add CSS declarations to an element.

First, we recommend doing the preceding View the CSS for an element tutorial.
Open the CSS Examples demo page in a new window or tab.
Right-click the Add A Background Color To Me! text, and then select Inspect.
Click element.style near the top of the Styles panel.
Type background-color or select it from the dropdown list and then press Enter.
Type honeydew or select it from the dropdown list of colors, and then press Enter. After you pick a color, an inline style declaration that's applied to the element is displayed in the DOM Tree.

The background-color:honeydew declaration is applied to the element using the element.style section of the Styles panel:

Add a CSS class to an element

To display how an element looks when a CSS class is applied to or removed from an element, see the Styles panel.

First, we recommend doing the preceding View the CSS for an element tutorial.
Open the CSS Examples demo page in a new window or tab.
Right-click the Add A Class To Me! text, and then select Inspect.
Click the Element Classes (.cls) button. DevTools shows a text box where you can add CSS classes to the page element that you're inspecting.
Type color_me in the Add new class text box, and then press Enter. A checkbox appears below the Add new class text box, where you can toggle the class on and off. If the Add A Class To Me! element has any other classes applied to it, you can also toggle each class from here.

The color_me class is applied to the element using the .cls section of the Styles panel:

Add a pseudostate to a class

Use the Styles panel to permanently apply a CSS pseudostate to an element. DevTools supports :active, :focus, :hover, and :visited.

First, we recommend doing the preceding View the CSS for an element tutorial.
Open the CSS Examples demo page in a new window or tab.
Hover over the Hover Over Me! text. The background color changes.
Right-click the Hover Over Me! text, and then select Inspect.
In the Styles panel, click the Toggle Element State (:hov) button.
Select the :hover checkbox. The background color changes like it did in the first step, even though you aren't actually hovering over the element.

The next screenshot shows the result of toggling the :hover pseudostate on an element.

Change the dimensions of an element

Use the Box Model interactive diagram in the Styles panel to change the width, height, padding, margin, or border length of an element.

First, we recommend doing the preceding View the CSS for an element tutorial.
Open the CSS Examples demo page in a new window or tab.
Right-click the Change My Margin! text, and then select Inspect.
In the Box Model diagram in the Styles panel, hover over padding. The element's padding is highlighted in the viewport.

Depending on the size of your DevTools window, you may need to scroll to the bottom of the Styles panel to display the Box Model.
Double-click the left margin in the Box Model, which currently has a value of -. The - means that the element doesn't have a value for margin-left.
Type 100px and press Enter. The Box Model defaults to pixels, but it also accepts other values, such as 25%, or 10vw.

Hovering over the element's padding:

Changing the element's left margin:

Debug media queries

CSS media queries are a way to make your website react to changes in the configuration settings for each user. The most common use case is to give your page a different CSS layout depending on the dimensions of the viewport.

Using separate layouts allows for a one-column layout for mobile devices and multi-column layouts when there's more screen real estate available.

To debug or test the media queries that you defined in your CSS:

Open the CSS Examples demo page in a new window or tab.
To open DevTools, right-click in the webpage and then select Inspect.
Click the Toggle device emulation () button. Or, when DevTools has focus, press Ctrl+Shift+M (Windows, Linux) or Command+Shift+M (macOS).

The device toolbar opens in the webpage, and the webpage is now rendered within the Device Emulation pane:
With the device toolbar open, click the More options () button on the top-right, and then select Show media queries:

The colored bars above the webpage represent the different media queries.
Hover over the boundaries in the bars to display the values of the different media queries. Click each media query value to resize the web page to match.
To open the CSS file that contains your media queries and edit their source code, right-click one of the colored bars and then select Reveal in source code. The Sources tool appears, and the corresponding media query is highlighted in the CSS file:

Note

Portions of this page are modifications based on work created and shared by Google and used according to terms described in the Creative Commons Attribution 4.0 International License. The original page is found here and is authored by Kayce Basques.

This work is licensed under a Creative Commons Attribution 4.0 International License.

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