Each shipping method and payment method in the list is accompanied with a couple of additional CSS classes:
active: If the method is currently selected by the customer;inactive: If the method is not currently selected by the customer;enabled: If the method is enabled in the Magento Admin Panel;disabled: If the method is disabled in the Magento Admin Panel;The last two CSS classes might be a bit confusing. For shipping methods, there is often a setting called Show Method if Not Applicable. If a method is not applicable but still shown, the CSS class disabled is shown. For payment methods, the same logic is used, except that there is no core logic to show a payment method while it is not applicable. If you don't care about this, it is best to ignore the CSS classes enabled and disabled.