Build a cookie consent banner.

PLACEMENT
Fixed to the bottom, full width, with padding-bottom: calc(1rem + env(safe-area-inset-bottom)). Above any bottom navigation. Do not use a full-screen modal that blocks the page — the visitor has not agreed to anything yet, including being interrupted.

CONTENT
One sentence stating what is stored and why. A link to the cookie policy. Then three controls of equal visual weight: Accept all, Reject all, and Manage.

Critical: Reject must be exactly as prominent as Accept — same size, same contrast, same position in the flow. A greyed-out reject button next to a bright accept button is a dark pattern and invalidates the consent it collects.

MANAGE PANEL
Expands in place rather than opening a new modal. Lists categories with individual toggles: Necessary (on, disabled, with an explanation of why), Analytics, Marketing. Everything except Necessary defaults to off. A save button applies exactly what is toggled.

BEHAVIOUR
Store the decision with a version number and a timestamp. Re-ask when the version changes. Fire no analytics or marketing scripts until consent exists — loading the script first and asking after defeats the entire point.

RULES
Fully keyboard operable, focus trapped inside the banner while it is open. Under prefers-reduced-motion, appear without the slide-up.