:root { color-scheme: light dark; --bg: #f6f7f9; --fg: #1d2330; --muted: #5b6475; --accent: #4f5bd5; }
@media (prefers-color-scheme: dark) { :root { --bg: #0f131c; --fg: #e8ebf2; --muted: #9aa3b5; --accent: #9aa4ff; } }
body { margin: 0; min-height: 100vh; display: grid; place-items: center; background: var(--bg); color: var(--fg);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", "Malgun Gothic", sans-serif; padding: 0 16px; }
main { max-width: 26rem; text-align: center; }
h1 { font-size: 1.3rem; margin: 0 0 .5rem; }
#lead, #note { color: var(--muted); margin: 0 0 1rem; }
#code { font: 700 2.6rem/1.2 ui-monospace, "Cascadia Mono", Consolas, monospace; letter-spacing: .08em; margin: 1rem 0; }
button { font: inherit; padding: .6rem 1.4rem; border-radius: .5rem; border: 1px solid var(--accent); background: transparent; color: var(--accent); cursor: pointer; }
button:disabled { opacity: .5; cursor: default; }