March 22, 2023

How To Add, Edit & Customize CSS In WordPress

Cascading style sheets (CSS) make it possible to modify the appearance of your website and create something truly unique.

Cascading style sheets (CSS) make it possible to modify the appearance of your website and create something truly unique. 

One of the simplest ways to add, edit, and customize CSS is using WordPress. Not sure how to use custom CSS in WordPress? Don’t worry — we’ve got you covered with a quick-start guide that digs into how CSS works, why it matters for your site, and how to edit CSS in WordPress.

What Is Custom CSS?

CSS is written in HTML and lets website owners and administrators change the appearance of a website. Using CSS, modifiers for color, size, layout, and other properties can be assigned to HTML tags. These tags determine both what is displayed on your website and how it will appear.

For example, the <header> tag is an HTML element that specifies the type and text of a header. By adding CSS classes to this tag, site owners can alter the size, text color, background color, and font type of the header. 

Custom CSS is simply the application of CSS modifiers to specific HTML elements that help give sites a unique look and feel.  

Reasons to Add Custom CSS

Custom CSS lets site owners tackle a host of tasks, from making small changes to completely redesigning a website. The versatile nature of CSS means there are multiple reasons to add and adjust these HTML modifiers, including:

Improved Site Impact

Default site designs are often bland and boring. For example, text is typically in black with white backgrounds, while links are in blue. Arial, Helvetica, and Times New Roman are common fonts, and media often takes the form of a few stock photos. Understandably, this offers little incentive for users to stay. 

With custom CSS, however, you can design a website that reflects your company’s style, color palette, and branding and make it more likely that when users arrive, they’re encouraged to stay.

Increased Visitor Engagement

Along with improved site impact, adding CSS can also help boost user engagement. For example, using CSS to customize and highlight key links — such as those for on-sale product pages or “contact us” forms — makes it easier for visitors to find what they’re looking for, in turn encouraging them to interact with your site and spend more time exploring what you have to offer.  

A/B Testing

With so many options to change the look and feel of your website, it’s easy to get overwhelmed by choice. While a new font or different color scheme might improve user impressions of your site, it could also cause a drop in new visitors or their engagement.

The granular nature of CSS, however, makes it possible for site owners to carry out A/B testing — modeling and trying out two versions of a format or function to see which one users prefer. When it comes to a website, this could take the form of something as simple as your site’s background color. With CSS, you can easily modify the color from standard white to another color of your choice. Then, track how many users the site attracts and how long they stay for each version, and pick the one that performs best.

Repeat this process for images, fonts, and any other styles on your site.

How to Edit or Add Custom CSS in WordPress

While it’s possible to add custom CSS using a specialized tool or simply make changes via your web browser, these methods can be complex and time-consuming. If you have a WordPress site, however, it’s possible to add or edit CSS in WordPress to streamline the process.

Want to add custom CSS to WordPress? Four approaches are common.

Theme Customizer

One way to edit CSS in WordPress is by using the built-in theme customizer. Available in WordPress versions 4.7 and later, the Theme Customizer allows you to add custom pieces of CSS code to your current WordPress Theme.

To access the Customizer, head to the Appearance section of your WordPress dashboard, then Customize. From there, scroll down and find Additional CSS. This will let you add custom CSS code to your site and preview both the mobile and desktop versions. 

Worth noting? You will need some experience with CSS to make best use of the Customizer, and any changes you make only apply to your current theme.

Full-Site Editor/Block Editor Features

Two other built-in options for adding CSS to your WordPress site are the full-site editor (FSE) and the block editor feature.

The FSE allows you to directly modify the CSS classes on your site without the need to write or add the CSS modifiers yourself. To access it, simply click on the Edit Site link in the WordPress administrator taskbar. To access the FSE, you’ll need WordPress 5.9 or later.

The block editor, meanwhile, allows you to select any content block on your WordPress site – from headers to paragraphs to images — and add CSS specific to that block. To use this feature, go to Appearance, then Site Editor. Next, select the block you want to customize and click on the settings button in the top-right of the screen, which looks like a small gear. Then, open the Advanced menu and look for the Additional CSS Class(es) section, and insert the CSS class of your choice.


Plugins offer another way to add and edit CSS in WordPress. Well known for its plugin ecosystem, WordPress makes it easy to install and use approved third-party programs for customization. Three popular plugin options include SiteOrigin CSS, WP Add Custom CSS, and Simple Custom CSS. There are also a host of other plugins available on WordPress marketplaces.

Child Theme

You can also add custom CSS using what’s known as a child theme. These themes are tied to their parent themes but can be modified without affecting the original, allowing you to test CSS functionality before implementing it on your live site. 

To create a child theme, head to the File Manager section of your hosting provider’s dashboard. From there, head to the public_html –> wp-content –> themes folder, and then click on New Folder. Give your child theme a name and click Create. Now, you can create a custom style.css file that will modify the appearance of your child theme without changing the parent, letting you see the impact of any CSS changes.

Making Most of Custom CSS in WordPress

To implement custom CSS in WordPress, first find a reliable and reputable WordPress hosting provider. Then, decide what needs to change on your website, and choose a custom CSS method that works for you.

Next up is testing. Experiment using temporary and test pages to see what works, what doesn’t, and where changes have the biggest impact. Once you’ve found the ideal combination, go live with your new page(s). It’s also a good idea to regularly review website performance — did your changes drive new visitors to the site? Did they stay longer and interact with more features? If so, your custom CSS was successful. If not, it’s easy to make changes and try again.

Ready to boost site impact and stand out from the crowd? Get started with custom CSS in WordPress.

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