body { max-width: 720px; margin: 40px auto; padding: 0 16px; font-family: system-ui, sans-serif; }
.card { border: 1px solid #ddd; border-radius: 8px; padding: 16px; margin: 16px 0; }
button { padding: 8px 14px; font-size: 16px; cursor: pointer; }
#local-clock { font-family: monospace; font-size: 20px; }