Yes, absolutely! You can change the color of any element in the booking form to match your business' branding.
You can edit this under the "Set Up" tab and choose on "Online Booking Forms" where you can choose the option for "Custom Theme" agains the booking form you're looking to adjust:
You can click on the "Advanced Color Options & CSS" where you can edit the colors:
As you click on any element's color, a color picker will appear:
As you make changes to the colors, the preview of the booking form to the right will update as you make changes. However, don't worry, changes are not published live to your website until you click the "Save Changes" button.
You can also add custom CSS under the same page: