Build a passkey-first sign-in card with Tailwind CSS: a prominent 'Sign in with a passkey' button that triggers the browser biometric prompt, the account avatar or user hint above it, and a quiet 'Use password instead' link below. Show a spinner state on the button while the authenticator is waiting, and if it fails, surface an inline error and expand the password form in place.
提示词保持英文原文——直接粘贴进 Claude、Cursor、v0 或任何 AI 编程工具即可使用。