functions.php

<?php
/**
 * ykolokas functions and definations.
 */

if ( ! function_exists( 'ykolokas_setup' ) ) {
    /**
     * Sets up theme defaults and registers support for various WordPress features.
     * 
     * Note that this function is hooked into the after_setup_theme hook, which
     * runs before the init hook. The init hook is too late for some features, such
     * as indicating support for post thumbnails.
     */
    function ykolokas_setup() {
        /**
         * Make theme available for translation
         * Translations can be filed in the /languages/ directory.
         * If you're building a theme on Crafty Press, use find and replace
         * to change 'ykolokas' to the name of your theme in all te template files.
         */
        load_theme_textdomain( 'ykolokas', get_template_directory() . '/languages' );

        // Add default posts and comments RSS feed links to head.
        add_theme_support( 'automatic-feed-links' );

        /**
         * Let WordPress manage the document title.
         * By adding theme support, we declare that this theme does not use a 
         * hard-coded <title> tag in the document head, and expect WordPress to
         * provde it for us.
         */
        add_theme_support( 'title-tag' );

        // Set up WordPress core custom backgrund feature
        add_theme_support( 'custom-background', 
            apply_filters( 'ykolokas_custom_background_args', 
                array(
                    'default-color' => '24010D',
                    'default-image' => '',
                )
            ) 
        );

        /**
         * Switch default core markup for search form, comment form and comments
         * to output valid HTML5
         */
        add_theme_support( 'html5', 
            array(
                'search-form',
                'comment-form',
                'comment-list',
                'gallery',
                'caption',
            )
        );

        // Add theme support for selective refresh for widgets.
        add_theme_support( 'customize-selective-refresh-widgets' );

        // Add support for core custom logo
        add_theme_support( 'custom-logo', [
            'height' => 250,
            'width' => 250,
            'flex-width' => true,
            'flex-height' => true,
        ] );

        // Add support for Custom Page Header
        add_theme_support( 'custom-header',
            array(
                'flex-width' => true,
                'width' => 1600,
                'flex-height' => true,
                'height' => 450,
                'default-image' => '',
            ) 
        );

        // Add Post Type Support
        add_theme_support( 'post-formats', [
            'aside',
            'gallery',
            'link',
            'image',
            'quote',
            'video',
            'audio',
        ] );

        // Enable support of featured image
        add_theme_support( 'post-thumbnails' );

        // This theme uses wp_nav_menu() in one location
        register_nav_menus( array(
            'primary' => esc_html__( 'Primary', 'ykolokas' ),
            'footer' => esc_html__( 'Footer', 'ykolokas' ),
        ) );
    }
}

add_action( 'after_setup_theme', 'ykolokas_setup' );

/**
 * Set the content width in pixels, based on the theme's design and stylesheet.
 * 
 * Priority 0 to make it available to lower priority callbacks.
 * 
 * @global int $content_width
 */
function ykolokas_content_width() {
    // This variable is intended to be evaluate from themes.
    // Open WPCS issue: {@link https://github.com/WordPress-Coding-Standards/issues/1043}.
    // phpcs:ignore WordPress.NamingConventions.PrfixAllGlobals.NonPrefixVariableFound
    $GLOBALS['content-width'] = apply_filters( 'ykolokas_content_width', 1280 );
}

add_action( 'after_setup_theme', 'ykolokas_content_width', 0 );

/**
 * Register Sidebar widget area.
 * 
 * @since 1.0.0
 */
function ykolokas_sidebar_widgets_init() {
    // Default Sidebar
    register_sidebar( array(
        'name'          => esc_html__( 'Sidebar', 'ykolokas' ),
        'id'            => 'default-sidebar',
        'description'   => esc_html__( 'Add widgets here.', 'ykolokas' ),
        'before_widget' => '<section id="%1$s" class="widget %2$s">',
        'after_widget'  => '</section>',
        'before-titel'  => '<h4 class="widget-title">',
        "after-title"   => '</h4>',
    ) );
}

add_action( 'widgets_init', 'ykolokas_sidebar_widgets_init' );

/**
 * Enqueue public scripts and styles
 */
function ykolokas_public_scripts() {
    // Styles
    wp_enqueue_style( 'default', get_template_directory_uri() . '/assets/css/default.css', [], wp_rand(), 'all' );
    wp_enqueue_style( 'main', get_template_directory_uri() . '/assets/css/main.css', [], wp_rand(), 'all' );

    // Scripts
    wp_enqueue_script( 'main', get_theme_file_uri('assets/js/main.js'), [ 'jquery' ], wp_rand(), true );
}
add_action( 'wp_enqueue_scripts', 'ykolokas_public_scripts' );

/**
 * Enqueue admin scripts and styles
 */
function ykolokas_admin_scripts() {

}
add_action( 'admin_enqueue_scripts', 'ykolokas_admin_scripts' );