How to add custom fonts in the editor

[strarsis]

You either have to ensure the path is stylesheet-relative for editor-stylesheets, or you enqueue these frontend styles as editor styles - by its path instead of URI - to let the Gutenberg editor post-process the styles and rewrite the URLs used therein:

Absolute / domain-relative path for asset URLs in CSS

With latest roots/acorn release version 2.1.1 the assets now have a relativePath() function, which simplifies this code a lot: namespace App; use function Roots\asset; add_action('after_setup_theme', function () { // Add frontend styles as editor styles // Must be added by relative path (not remote URI) // (@see https://core.trac.wordpress.org/ticket/55728#ticket) $relCssPath = asset('app.css')->relativePath(get_theme_file_path()); add_editor_style($relCssPath); });