:root { color-scheme: light dark; font-family: system-ui, sans-serif; }
body { margin: 0; }
.shell, .gate { max-width: 640px; margin: 0 auto; padding: 24px; }
nav { display: flex; gap: 16px; margin-bottom: 24px; }
form { display: flex; flex-direction: column; gap: 12px; max-width: 360px; }
input { padding: 8px; }
.error { color: crimson; }