WooCommerce checkout scattered styles

I have an problem with scattered styles in WooCommerce checkout

I think in code it's okay but I updated from some version of WooCommerce before 3.5.0 and now I have so scattered design on checkout..

Take a look on image here:

The code of form-checkout.php is:

<div class="col-md-8 mb-3">

    <div class="sh p-5 ovh">
        <div class="">
            <?php if ($checkout->get_checkout_fields()) : ?>

                <?php do_action('woocommerce_checkout_before_customer_details'); ?>

                <div class="col2-set" id="customer_details">
                    <div class="col-1">
                        <?php do_action('woocommerce_checkout_billing'); ?>
                    </div>

                    <div class="col-2">
                        <?php do_action('woocommerce_checkout_shipping'); ?>
                    </div>
                </div>

                <?php do_action('woocommerce_checkout_after_customer_details'); ?>

            <?php endif; ?>


        </div>
    </div>

</div>

In code everything looks okay, I tried google but found nothing about this specific problem.. Any advices?