Please test now.
I have added this CSS to your child theme:
.woocommerce-cart.woocommerce .container {
padding: 0;
}
And updated the PHP to:
// Remove each style one by one
add_filter( 'woocommerce_enqueue_styles', 'jk_dequeue_styles' );
function jk_dequeue_styles( $enqueue_styles ) {
if( is_checkout() || is_cart() ) {
unset( $enqueue_styles['woocommerce-smallscreen'] ); // Remove the smallscreen optimisation
}
return $enqueue_styles;
}