New Mollie Checkout design

We're starting to roll out a fresh Mollie Checkout design, beginning with new customers and updating the existing checkouts shortly:

• Two-column layout — if line-items are available they will be shown side by side with available payment methods for a cleaner overview.
• "Show more" for payment methods — keeps the checkout tidy when many payment methods are available.
• Custom background removed — a cleaner, more polished look that removes clutter for an improved checkout experience.