Unexpected changes to Squarespace cart page markup

At 17:00 GMT today, Squarespace rolled out a change today that inadvertently caused changes to the HTML structure of the cart page on all Squarespace 7.0 and 7.1 websites.

Squarespace engineers apologised for the disruption afterwards as they had misjudged the impact of this routine change and so didn’t notify us of this change in advance. Instead of a “no customer impact” change, the rollout caused the non-semantic, compiler-generated class names on the cart page to change to new random values. Semantic names were unaffected.

This change affects all cart page custom code including third party extensions, plugins, code snippets and custom CSS.