'',
		'font-style'   => 'normal',
		'font-weight'  => '400',
		'font-display' => 'fallback',
	);
	/**
	 * Valid font-face property names.
	 *
	 * @since 6.4.0
	 *
	 * @var string[]
	 */
	private $valid_font_face_properties = array(
		'ascent-override',
		'descent-override',
		'font-display',
		'font-family',
		'font-stretch',
		'font-style',
		'font-weight',
		'font-variant',
		'font-feature-settings',
		'font-variation-settings',
		'line-gap-override',
		'size-adjust',
		'src',
		'unicode-range',
	);
	/**
	 * Valid font-display values.
	 *
	 * @since 6.4.0
	 *
	 * @var string[]
	 */
	private $valid_font_display = array( 'auto', 'block', 'fallback', 'swap', 'optional' );
	/**
	 * Array of font-face style tag's attribute(s)
	 * where the key is the attribute name and the
	 * value is its value.
	 *
	 * @since 6.4.0
	 *
	 * @var string[]
	 */
	private $style_tag_attrs = array();
	/**
	 * Creates and initializes an instance of WP_Font_Face.
	 *
	 * @since 6.4.0
	 */
	public function __construct() {
		if (
			function_exists( 'is_admin' ) && ! is_admin()
			&&
			function_exists( 'current_theme_supports' ) && ! current_theme_supports( 'html5', 'style' )
		) {
			$this->style_tag_attrs = array( 'type' => 'text/css' );
		}
	}
	/**
	 * Generates and prints the `@font-face` styles for the given fonts.
	 *
	 * @since 6.4.0
	 *
	 * @param array[][] $fonts Optional. The font-families and their font variations.
	 *                         See {@see wp_print_font_faces()} for the supported fields.
	 *                         Default empty array.
	 */
	public function generate_and_print( array $fonts ) {
		$fonts = $this->validate_fonts( $fonts );
		// Bail out if there are no fonts are given to process.
		if ( empty( $fonts ) ) {
			return;
		}
		$css = $this->get_css( $fonts );
		/*
		 * The font-face CSS is contained within  and open a