:root { --bg: #f6f7f9; --fg: #1d2330; --muted: #5b6475; --line: #dde1e8; --accent: #b00020; --card: #fff; }
@media (prefers-color-scheme: dark) {
  :root { --bg: #14171d; --fg: #e8ebf0; --muted: #9aa3b2; --line: #2c323d; --accent: #ff6b7f; --card: #1c2028; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 16px/1.6 -apple-system, "PingFang TC", "Noto Sans TC", sans-serif; }
main { max-width: 560px; margin: 0 auto; padding: 32px 16px; }
h1 { font-size: 24px; margin: 0 0 4px; }
.sub { color: var(--muted); margin: 0 0 20px; font-size: 14px; }
.levels { list-style: none; padding: 0; margin: 0; }
.levels li { display: flex; justify-content: space-between; align-items: center; gap: 12px;
  background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 14px 16px; margin-bottom: 10px; }
.levels a { color: var(--fg); font-weight: 600; text-decoration: none; font-size: 18px; }
.levels a::after { content: " ›"; color: var(--muted); }
.levels span { color: var(--muted); font-size: 13px; }
.levels .empty { color: var(--muted); justify-content: center; }
button { font: inherit; width: 100%; padding: 14px; border-radius: 12px; border: 0; background: var(--accent); color: #fff; font-weight: 600; margin-top: 12px; }
button.ghost { background: transparent; color: var(--muted); border: 1px solid var(--line); }
.code { font: 700 40px/1.2 ui-monospace, Menlo, monospace; letter-spacing: 6px; text-align: center; margin: 12px 0; }
.err { color: var(--accent); min-height: 1.5em; }