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Editor and content styles

CKEditor 5 is distributed with two types of styles:

  • Editor styles, used to style the editor’s user interface.
  • Content styles, used to style the content in the editor.

If you went through our Quick start, you probably noticed that attaching the styles in JavaScript is pretty standard, and we provide CSS style sheets that have both the editor and content styles combined:

import 'ckeditor5/ckeditor5.css';

// If you are using premium features:
import 'ckeditor5-premium-features/ckeditor5-premium-features.css';

It is as easy in HTML if you decide to use our CDN:

<link rel="stylesheet" href="https://cdn.ckeditor.com/ckeditor5/44.1.0/ckeditor5.css" />

<!-- If you are using premium features: -->
<link rel="stylesheet" href="https://cdn.ckeditor.com/ckeditor5-premium-features/44.1.0/ckeditor5-premium-features.css" />

# Why do I need content styles?

Some core editor features bring additional CSS to control the look of the content they produce. One of such examples is the image feature that needs special content styles to render images and their captions in the content. Another would be the block quote feature that displays quotes in italics with a subtle border on the side. You can see both of these pictured below.

Editor content styles.

# Customizing the editor’s look

The @ckeditor/ckeditor5-theme-lark package contains the default theme of CKEditor 5. Lark is modular, BEM–friendly and built using PostCSS.

Although it was designed with versatility and the most common editor use cases in mind, some integrations may require adjustments to make it match the style guidelines of their ecosystems. This kind of customization can be done by importing an extra .css file and overriding the native CSS variables.

For example, the override below will tweak the border radius of several elements in the editor, such as toolbar or contextual balloons.

:root {
    /* Overrides the border radius setting in the theme. */
    --ck-border-radius: 4px;
}

Check out the color sheet for a full list of customizable colors. You can also browse other files to learn about other useful tools.

# Customizing the look of the features

Similarly to the customizable editor look, some features also provide an interface to change their styles via native CSS variables.

For example, if you want to change the color of the mentions’ background and text, you can do the following override:

:root {
    --ck-color-mention-background: black;
    --ck-color-mention-text: white;
}

Find the available CSS variables in our ckeditor5 and ckeditor5-premium-features packages.

# Styling the published content

Your application is typically divided into two areas. Content creation, which hosts the editor and is a writing tool, and content publishing, which presents the written content.

It is important to use the content styles on the publishing side of your application. Otherwise, the content will look different in the editor and for your end users.

There are two ways to obtain the content styles:

  • From the npm packages, in the dist/ckeditor5-content.css and ckeditor5-premium-features-content.css location.
  • From our CDN, https://cdn.ckeditor.com/ckeditor5/

Below is an example with placeholder paths showing how to load the ckeditor5-content.css (and ckeditor5-premium-features-content.css, if needed) file on the publishing side.

<link rel="stylesheet" href="path/to/assets/ckeditor5-content.css">

<!-- If you are using premium features: -->
<link rel="stylesheet" href="path/to/assets/ckeditor5-premium-features-content.css">

<!-- If you have other style sheet that changes the look of the content: -->
<link rel="stylesheet" href="path/to/assets/styles.css">

The final setup depends on how your application is structured. As mentioned earlier, you can use our CDN, or your JS bundler already creates and serves combined style sheets. Choose the solution that works best for your case.

Important!

If you take a closer look at the content styles, you may notice they are prefixed with the .ck-content class selector. This narrows their scope when used in CKEditor 5 so they do not affect the rest of the application. To use them in the front–end, you will have to add the ck-content CSS class to the container of your content. Otherwise, the styles will not be applied.

# Optimizing the size of style sheets

The ckeditor5 package distributes three style sheets:

  • ckeditor5.css – combined editor and content styles,
  • ckeditor5-content.css – only content styles,
  • ckeditor5-editor.css – only editor styles.

The same is true for the ckeditor5-premium-features package, but the filenames are different:

  • ckeditor5-premium-features.css – combined editor and content styles,
  • ckeditor5-premium-features-content.css – only content styles,
  • ckeditor5-premium-features-editor.css – only editor styles.

However, these style sheets include styles for all editor plugins. If you want to optimize the size of the style sheet, to only include styles for the plugins you use, you can follow the Optimizing build size guide.