Adds callback for custom TinyMCE editor stylesheets.
Description
The parameter $stylesheet is the name of the stylesheet, relative to the theme root. It also accepts an array of stylesheets.
It is optional and defaults to ‘editor-style.css’.
This function automatically adds another stylesheet with -rtl prefix, e.g. editor-style-rtl.css.
If that file doesn’t exist, it is removed before adding the stylesheet(s) to TinyMCE.
If an array of stylesheets is passed to add_editor_style() , RTL is only added for the first stylesheet.
Since version 3.4 the TinyMCE body has .rtl CSS class.
It is a better option to use that class and add any RTL styles to the main stylesheet.
Parameters
$stylesheet
array|stringoptional- Stylesheet name or array thereof, relative to theme root.
Defaults to'editor-style.css'
Default:
'editor-style.css'
Source
function add_editor_style( $stylesheet = 'editor-style.css' ) {
global $editor_styles;
add_theme_support( 'editor-style' );
$editor_styles = (array) $editor_styles;
$stylesheet = (array) $stylesheet;
if ( is_rtl() ) {
$rtl_stylesheet = str_replace( '.css', '-rtl.css', $stylesheet[0] );
$stylesheet[] = $rtl_stylesheet;
}
$editor_styles = array_merge( $editor_styles, $stylesheet );
}
Changelog
Version | Description |
---|---|
3.0.0 | Introduced. |
Basic Example
Add the following to the functions.php file of your theme.
Next, create a file named custom-editor-style.css in your themes root directory. Any CSS rules added to that file will be reflected within the TinyMCE visual editor. The contents of the file might look like this:
add_editor_style()
internally adds not the same theme supports string that you’ve meant to add manually. From the Editor styles docs, this is what you should add:add_theme_support( 'editor-styles' );
. And this is what is called insideadd_editor_style()
function:add_theme_support( 'editor-style' );
. Notice the “missing” “s” character at the end.# Gutenberg
This works with Gutenberg. Your CSS will be added as inline styles. All selectors will be prefixed with:
.editor-styles-wrapper
(exceptbody
, see below).All the info below is related to using this function with Gutenberg.
# Body Styles
Styles targeting the body will be changed to target
.editor-styles-wrapper
instead. This lets you to customise the Gutenberg editor pane directly, e.g. to change its padding. You can also set defaults (like font family, color, etc) by adding styles to the body class.Example:
body { color: red }
becomes.editor-styles-wrapper { color: red }
# CSS Resets
If you’re using the same stylesheet for both your frontend and editor styles, be careful about using a CSS reset. It will affect all elements within the editor, including admin controls for blocks ─ such as TinyMCE’s GUI buttons in the Classic block, or ACF block fields in edit mode.
You may prefer to move your reset of your main styles and enqueue it independently on the frontend instead, perhaps with a dedicated, customized reset for the editor.
# Using @import
I’ve seen developers report that using
@import
in your CSS causes issues. If this happens to you, it would be better to add the imported file by other means, either as an additional array item inadd_editor_style
, or by enqueuing it as an admin style on just editor pages (see other user notes that use$pagenow
for this).# Local Development + SSL
If you’re working locally, be aware that using an absolute URL (eg. via get_template_directory_uri) won’t work if you’re using HTTPS with a self-signed certificate. This is due to wp_remote_get being used to retrieve your stylesheet, which fails (silently) if a requested URL’s certificate isn’t included in WordPress’ internal store of allowed certificates.
Workarounds include: Using a path relative to your theme root instead (ideal), using an absolute HTTP URL instead of HTTPS, and disabling the SSL verification with https_ssl_verify (not recommended for security reasons).
# Code Context
The code that retrieves the styles uses either wp_remote_get for absolute URLs, or
file_get_contents
for files relative to the theme root. You can find this code in block-editor.php, at the functionget_block_editor_theme_styles()
. It’s called from edit-form-blocks.php.$relative_path = str_replace( WP_CONTENT_URL, '../..', $url ); add_editor_style( $relative_path );
If you want to add styles dynamically (eg. from theme mods) you can use the tiny_mce_before_init filter and add them to the content_style key.
Note that any new lines or double quotes should be removed or double escaped in your CSS.
Using Google Fonts
Google Fonts API provides a single URL for a CSS file that can include multiple variants of a type face, separated by commas. Commas in a URL need to be encoded before the string can be passed to add_editor_style.
Choosing Styles Based on Post Type
To link a custom editor stylesheet file based on the post type being edited, you can use the following in the functions.php file of your theme. This assumes the stylesheet files with names in the form of editor-style-{post_type}.css are present directly under your theme directory.
Note that the pre_get_posts action hook is used to ensure that the post type is already determined but, at the same time, that TinyMCE has not been configured yet. That hook is not run when creating new posts, that is why we need to use it in combination with the init hook to achieve a consistent result.
If you are keeping your style files in a sub-directory, eg, css, you add the editor style with:
Using Gutenberg, calling
add_theme_support( 'editor-styles' );
is required before callingadd_editor_style()
, even though the function is supposed to add theme support for editor styles.So if you want to add your own styles to the Gutenberg editor, be sure to call both functions:
To add styles from a plugin use a URL in place of a path relative to the theme root.
Note that the Block Editor is unable to parse any file containing CSS @layers. Using CSS layers will prevent the entire file from being applied to the editor. Ex:
The example above can be rewritten simpler:
Reusing Your Theme Styles
You can reuse the styles from your theme stylesheet file in your custom editor stylesheet file using the @import CSS rule. Working on the previous example, put the following instead into the custom-editor-style.css file.
If necessary, change ‘style.css’ to the path to your theme stylesheet, relative to the custom-editor-style.css file.