:root {
  --paper: #f2f2f7;
  --card: #ffffff;
  --ink: #111114;
  --muted: #6b6b73;
  --line: #e2e2e8;
  --accent: #047857;
  --on-accent: #ffffff;
  --accent-soft: #d1fae5;
  --notice: #fef3c7;
  --on-notice: #78350f;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #000000;
    --card: #1c1c1e;
    --ink: #f2f2f7;
    --muted: #a1a1aa;
    --line: #2c2c30;
    --accent: #34d399;
    --on-accent: #052e1f;
    --accent-soft: #063d2c;
    --notice: #3a2a06;
    --on-notice: #fde68a;
  }
}
:root[data-theme="dark"] {
  --paper: #000000;
  --card: #1c1c1e;
  --ink: #f2f2f7;
  --muted: #a1a1aa;
  --line: #2c2c30;
  --accent: #34d399;
  --on-accent: #052e1f;
  --accent-soft: #063d2c;
  --notice: #3a2a06;
  --on-notice: #fde68a;
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 17px/1.45 -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC", "Hiragino Sans GB", "Helvetica Neue", Arial, sans-serif;
}
main {
  max-width: 480px;
  margin: 0 auto;
  padding: max(24px, env(safe-area-inset-top)) 16px max(32px, env(safe-area-inset-bottom));
}
.brand { display: flex; align-items: center; gap: 12px; margin-bottom: 28px; }
.brand img { border-radius: 11px; }
.brand .name { font-weight: 600; font-size: 20px; }
.brand .tagline { color: var(--muted); font-size: 15px; }

h1 { font-size: 28px; line-height: 1.2; margin: 0 0 8px; font-weight: 700; }
h2 { font-size: 20px; margin: 36px 0 8px; font-weight: 600; }
.lead { color: var(--muted); margin: 0 0 20px; }
.muted { color: var(--muted); display: block; margin-top: 4px; font-size: 15px; }
.hint { color: var(--muted); font-size: 13px; text-align: center; margin: 8px 0 0; }

.notice {
  background: var(--notice);
  color: var(--on-notice);
  border-radius: 12px;
  padding: 12px 14px;
  font-size: 15px;
  margin: 0 0 20px;
}

.code-box {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 16px;
  text-align: center;
  margin-bottom: 16px;
}
.code-box .label { color: var(--muted); font-size: 13px; }
.code {
  font-size: 34px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  margin: 4px 0;
  user-select: all;
  -webkit-user-select: all;
}

.button {
  display: block;
  text-align: center;
  text-decoration: none;
  border-radius: 14px;
  padding: 14px 16px;
  font-weight: 600;
  background: var(--accent-soft);
  color: var(--ink);
  margin-top: 8px;
}
.button.primary { background: var(--accent); color: var(--on-accent); font-size: 17px; }
button.link {
  border: 0;
  background: none;
  color: var(--accent);
  font: inherit;
  font-size: 15px;
  font-weight: 600;
  padding: 6px 10px;
  cursor: pointer;
}

.steps { padding-left: 22px; margin: 0; }
.steps li { margin: 0 0 12px; }

.home h1 { margin-top: 8px; }
.home p { color: var(--muted); }