public function add_custom_css() {

    $media_query = esc_attr( $this->extras_config['media_query_width'] );
    $extra       = $this->extras_config['css'];

    $css = sprintf(
      '
			/* Genesis+AMP responsive menu styles.
			--------------------------------------------- */
			@media only screen and (min-width: %1$s) {
				.menu-item.genesis-amp-combined { display: none }
			}

			@media only screen and (max-width: %1$s) {
				.header-menu .genesis-responsive-menu,
				.genesis-responsive-menu {
					display: block;
					position: absolute;
					left: -9999px;
					opacity: 0;
					-webkit-transform: scaleY(0);
					-moz-transform: scaleY(0);
					-ms-transform: scaleY(0);
					-o-transform: scaleY(0);
					transform: scaleY(0);
					transform-origin: top;
					-webkit-transition: transform 0.2s ease;
					-moz-transition: transform 0.2s ease;
					o-transition: transform 0.2s ease;
					transition: transform 0.2s ease;
				}

				.genesis-nav-menu.responsive-menu.toggled-on,
				.genesis-responsive-menu.toggled-on {
					opacity: 1;
					position: relative;
					left: auto;
					-webkit-transform: scaleY(1);
					-moz-transform: scaleY(1);
					-ms-transform: scaleY(1);
					-o-transform: scaleY(1);
					transform: scaleY(1);
				}

				.genesis-responsive-menu.toggled-on .menu-item .sub-menu,
				.genesis-responsive-menu.toggled-on .menu-item:hover > .sub-menu {
					display: none;
				}

				.genesis-responsive-menu.toggled-on .sub-menu-toggle.toggled-on + .sub-menu {
					display: block;
					width: 100%%;
					-webkit-transform: scaleY(1);
					-moz-transform: scaleY(1);
					-ms-transform: scaleY(1);
					-o-transform: scaleY(1);
					transform: scaleY(1);
				}

				%2$s

			}',
      $media_query,
      $extra
    );

    
/**
 * Filter the CSS output.
 *
 * @since 3.1.1
 *
 * @param string $css         The default CSS output.
 * @param string $media_query The media query set in theme config.
 * @param string $extra       The extra CSS set in theme config.
 */
    $css = apply_filters( 'genesis_amp_menu_css', $css, $media_query, $extra );

    wp_add_inline_style( genesis_get_theme_handle(), $css );

  }