Add support for Gutenberg

GREAT Post -
https://themeshaper.com/2018/02/15/styling-themes-for-gutenberg/
https://themehybrid.com/weblog/align-wide-and-full-classes

/**
* Add support for Gutenberg.
*
* @link https://wordpress.org/gutenberg/handbook/reference/theme-support/
*/
add_theme_support( 'gutenberg', array(

    // Theme supports wide images, galleries and videos.
    'wide-images' => true,

    // Make specific theme colors available in the editor.
    'colors' => array(
        '#ffffff',
        '#000000',
        '#cccccc',
    ),

) );




@media (min-width: 750px) {

    .alignfull {
        margin-left: calc(50% - 50vw);
        margin-right: calc(50% - 50vw);
        width: auto;
        max-width: 1000%;
    }

    .alignwide {
        margin-left: calc(25% - 25vw);
        margin-right: calc(25% - 25vw);
        width: auto;
        max-width: 1000%;
    }

}

This approach works, but because vw includes the width of the vertical scrollbar as part of the whole screen width, you can get a little horizontal scrolling. One fix is adding overflow: hidden to one of the page-width elements further up the


/**
* Enqueue editor styles for Gutenberg
*/

function theme_slug_editor_styles() {
    wp_enqueue_style( 'theme-slug-editor-style', get_template_directory_uri() . '/assets/stylesheets/editor-style.css' );
}
add_action( 'enqueue_block_editor_assets', 'theme_slug_editor_styles' );


Like with the TinyMCE editor, you can also include fonts. So for example, if your theme is enqueuing fonts from Google, you can include them in the Gutenberg editor, too:

/**
* Enqueue editor styles for Gutenberg
*/

function theme_slug_editor_styles() {
    wp_enqueue_style( 'theme-slug-editor-style', get_template_directory_uri() . '/assets/stylesheets/editor-style.css' );
    wp_enqueue_style( 'theme-slug-fonts', theme_slug_fonts_url(), array(), null );
}
add_action( 'enqueue_block_editor_assets', 'theme_slug_editor_styles' );


The editor styles need to be pretty specific to make sure they’re not applied to other elements of the page outside of the editor — Rich Tabor has a good post here about his experience with this behavior. Gutenberg includes specific classes around different elements in the editor, so you can prefix selectors more generally with the class .editor-post-visual-editor, or use more specific classes to target individual blocks — for example, styles for .editor-block-list__block[data-type="core/heading"] h1 would only be applied to h1s