wbxpress-one theme's functions file.

functions.php

<?php

if ( ! isset( $content_width ) ) {
	$content_width = 550;
}

if ( ! function_exists( 'wbxpressone_setup' ) ) {
	function wbxpressone_setup() {
		
		add_theme_support( 'title-tag' );
		
		add_theme_support( 'html5', array(
			'search-form', 'comment-form', 'comment-list', 'caption'
		) );

		register_nav_menus( array(
			'primary' => __( 'Primary Navigation', 'wbxpress-one' ),
		));
	}
}
add_action( 'after_setup_theme', 'wbxpressone_setup' );

function wbxpressone_widgets_init() {
	register_sidebar( array(
		'name'          => __( 'Sidebar', 'wbxpress-one' ),
		'id'            => 'sidebar',
        'before_widget' => '<div id="%1$s" class="widget %2$s">',
        'after_widget'  => '</div>',
        'before_title'  => '<h4>',
        'after_title'   => '</h4>',
    ));
	
	register_sidebar( array(
		'name'          => __( 'Footer Left', 'wbxpress-one' ),
		'id'            => 'footer-left',
        'before_widget' => '<div id="%1$s" class="widget %2$s">',
        'after_widget'  => '</div>',
        'before_title'  => '<h4>',
        'after_title'   => '</h4>',
    ));
	
	register_sidebar( array(
		'name'          => __( 'Footer Center', 'wbxpress-one' ),
		'id'            => 'footer-center',
        'before_widget' => '<div id="%1$s" class="widget %2$s">',
        'after_widget'  => '</div>',
        'before_title'  => '<h4>',
        'after_title'   => '</h4>',
    ));
	
	register_sidebar( array(
		'name'          => __( 'Footer Right', 'wbxpress-one' ),
		'id'            => 'footer-right',
        'before_widget' => '<div id="%1$s" class="widget %2$s">',
        'after_widget'  => '</div>',
        'before_title'  => '<h4>',
        'after_title'   => '</h4>',
    ));
}
add_action( 'widgets_init', 'wbxpressone_widgets_init' );

function wbxpressone_scripts() {
	wp_enqueue_style( 'wbxpressone-style', get_stylesheet_uri(), array(), '1.0.0' );
	
	if ( is_singular() && comments_open() && get_option( 'thread_comments' ) ) {
		wp_enqueue_script( 'comment-reply' );
	}
}
add_action( 'wp_enqueue_scripts', 'wbxpressone_scripts' );

// ----------------------------------------------

if ( ! function_exists( '_wp_render_title_tag' ) ) {
	function theme_slug_render_title() {
		?>
		<title><?php wp_title( '|', true, 'right' ); ?></title>
		<?php
	}
	add_action( 'wp_head', 'theme_slug_render_title' );
	
	function wbxpressone_wp_title( $title, $sep ) {
		global $paged, $page;
		
		if ( is_feed() ) {
			return $title;
		}
		
		// Add the site name.
		$title .= get_bloginfo( 'name', 'display' );
		
		// Add the site description for the home/front page.
		$site_description = get_bloginfo( 'description', 'display' );
		if ( $site_description && ( is_home() || is_front_page() ) ) {
			$title = "$title $sep $site_description";
		}
		
		// Add a page number if necessary.
		if ( $paged >= 2 || $page >= 2 ) {
			$title = "$title $sep " . sprintf( __( 'Page %s', 'wbxpress-one' ), max( $paged, $page ) );
		}
		
		return $title;
	}
	add_filter( 'wp_title', 'wbxpressone_wp_title', 10, 2 );
}

if ( function_exists( 'the_posts_pagination' ) ) {
	the_posts_pagination( array(
		'prev_text'          => __( 'Previous', 'wbxpress-one' ),
		'next_text'          => __( 'Next', 'wbxpress-one' ),
		'before_page_number' => '',
	) );
} else {
	function the_posts_pagination() {
		?>
		<div class="navigation">
			<div class="nav-previous"><?php next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts', 'wbxpress-one' ) ); ?></div>
			<div class="nav-next"><?php previous_posts_link( __( 'Newer posts <span class="meta-nav">&rarr;</span>', 'wbxpress-one' ) ); ?></div>
		</div>
		<?php
	}
}

if ( function_exists( 'the_post_navigation' ) ) {
	the_post_navigation( array(
		'prev_text' => '%title',
		'next_text' => '%title',
		'screen_reader_text' => '',
	) );
} else {
	function the_post_navigation() {
		?>
		<div class="navigation">
			<div class="nav-previous"><?php previous_post_link( '%link', '<span class="meta-nav">' . __( '&larr;', 'wbxpress-one' ) . '</span> %title' ); ?></div>
			<div class="nav-next"><?php next_post_link( '%link', '%title <span class="meta-nav">' . __( '&rarr;', 'wbxpress-one' ) . '</span>' ); ?></div>
		</div><!-- #nav-below -->
		<?php
	}
}