KeenMerch answers
Does a sticky upsell bar break keyboard checkout?
It can. WCAG 2.2 asks that a focused button or field is never fully hidden by content you added. A bar pinned to the bottom of the screen often covers exactly that.
Where it goes wrong
A shopper using a keyboard tabs through the cart. The next field sits under your fixed upsell bar, so they cannot see what has focus. Success Criterion 2.4.11, Focus Not Obscured (Minimum), is a Level AA requirement in WCAG 2.2.
A safer pattern
Put the offer inline in the cart, not in a fixed layer. If you keep a sticky bar, add bottom padding equal to its height and let shoppers close it. Test by tabbing through the whole cart without a mouse.
Source
W3C, Web Content Accessibility Guidelines (WCAG) 2.2. Reviewed Sep 23, 2026.