body { margin: 0; min-height: 100vh; display: grid; place-items: center; font-family: system-ui, -apple-system, "Segoe UI", sans-serif; color: #1d232b; background: #f6f8fa; }
.sign-in { display: grid; gap: 0.6rem; width: min(20rem, 90vw); padding: 1.5rem; background: #fff; border: 1px solid #dde2e8; border-radius: 0.5rem; }
.sign-in h1 { margin: 0 0 0.5rem; font-size: 1.3rem; }
input, button { font: inherit; padding: 0.5rem; }
.error { color: #a01919; margin: 0; }