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Style Bold Checkout with CSS

  • Updated

Bold Checkout accepts standard-formatted CSS rules. This allows you to style your store's checkout experience to match your brand.

Note: CSS settings apply across all Bold-hosted checkout flows that exist on your store. 

This article outlines some common CSS changes and shows you where you can add your custom CSS in Bold Checkout.



Identify CSS changes

Identify the classes you want to change by inspecting the checkout page.

Some common CSS changes can be divided into several groups, outlined in the table below.



Sample Class Values


Adjust color and style of the clickable links and form fields.

Button, a, InputField, ToggleField__Input, AppliedDiscount_Code


Adjust the colors that appear when hovering over a button or link.

Button, a


Adjust the color of the background in one of two locations: behind the form fields, or behind the order summary.

Checkout__Main, Checkout__Summary


Adjust the color of the error that appears when a customer's input is invalid.



For example, to change the color of selected radio buttons to purple, you can use the following CSS:

.stx-radio-field .stx-radio--is-checked input {
box-shadow: 0 0 0 6px #7a5af5 inset;


Radio buttons

Payment Gateway Isolation Interface

The Payment Isolation Gateway Interface (PIGI) is the interface that your customer uses to input their payment information. It is rendered using an iframe in order to keep the payment information secure. You can make minor CSS changes to this interface as well.

CSS changes that impact the PIGI interface must use the identifier #iframe-payment-gateway.

For example, to apply the CSS rule from the previous section to PIGI, add the following to your CSS rules:

#iframe-payment-gateway .stx-radio-field .stx-radio--is-checked input {
box-shadow: 0 0 0 6px #7a5af5 inset;


CSS radio buttons pigi




To add your custom CSS to Bold Checkout, please follow the steps below.

  1. In Bold Checkout, navigate to Settings > General settings.
  2. Scroll down to the Appearance section.
  3. Enter your custom CSS into the Custom CSS field.

    Custom CSS field

  4. Click Save.