As an experienced Full Stack Web Developer, I have had the unique opportunity to work on various CMS platforms including Squarespace, and my understanding of custom CSS would definitely be an asset in delivering the sticky cart block functionality you desire for your Square website. I have the ability to ensure the checkout cart stays securely "stuck" in the right position on your page as well as maintain its visibility even while users scroll.
Throughout my 5 years in the field, I've honed a comprehensive skill set in not just CSS, but also HTML5, JavaScript and Bootstrap - all of which are highly applicable to this project. Plus, my expertise in front-end and back-end development means that any modifications won't damage other code within your site.
Lastly, I treat each client's project like it's my own–equipped with a commitment to safety, efficiency, and collaboration. This is why I believe we can spark off a positive long-term working relationship that'll benefit not only this particular Sticky Checkout Cart customization but any future projects you may require. I am available round-the-clock and offer one year of support post-project completion alongside a 100% satisfaction guarantee or your money back; so let’s begin our productive journey together today!