Change WooCommerce Email style

/**
 * Change WooCommerce Email Styles
 */
function twstudio_woocommerce_email_styles( $css ) {
   $css .= "
   
   //Custom css goes here

   ;
   return $css;
}
add_filter( 'woocommerce_email_styles', 'twstudio_woocommerce_email_styles' );