AFTER – the fix applied
Identical checkout form, identical Astra Palette 4, identical dark-mode CSS as the BEFORE page. The only difference is the stylesheet below, which puts SureCart’s own colour tokens back where Astra’s dark-mode compatibility layer overwrote them. Labels, typed text and the order summary are all readable again, and nothing else on the site changes.
On this demo the rule is scoped to this one page so the BEFORE page still shows the problem. On a real site you drop the .page-id-425 part so it applies everywhere.