:root {
  --bg: #f8fafc;
  --card: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --accent: #2563eb;
  --accent-contrast: #ffffff;
  --radius: 18px;
}
* { box-sizing: border-box; }
html, body {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: var(--bg);
}
.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px;
}
header {
  text-align: center;
  margin: 16px 0 28px;
}
h1 {
  font-size: clamp(1.6rem, 2.5vw + 1rem, 2.4rem);
  margin: 0 0 8px;
}
p.sub {
  margin: 0;
  color: var(--muted);
  font-size: 1.05rem;
}
.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}
@media (min-width: 640px) {
  .grid { grid-template-columns: 1fr 1fr; }
}
.card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: 0 8px 28px rgba(2, 6, 23, 0.06);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}
.card h2 {
  margin: 10px 0 12px;
  font-size: 1.4rem;
}
.card p { color: var(--muted); margin: 0 0 16px; }
.btn {
  display: inline-block;
  font-weight: 700;
  text-decoration: none;
  background: var(--accent);
  color: var(--accent-contrast);
  padding: 14px 18px;
  border-radius: 999px;
  font-size: 1.05rem;
  box-shadow: 0 6px 22px rgba(37, 99, 235, 0.25);
  width: 100%;
  text-align: center;
}
.btn:active { transform: translateY(1px); }
footer {
  margin-top: 28px;
  text-align: center;
  color: var(--muted);
  font-size: 0.95rem;
}
.tip {
  margin-top: 12px;
  font-size: 0.95rem;
  color: var(--muted);
}
.hero {
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: 14px;
  background: linear-gradient(135deg, #dbeafe, #f5d0fe);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
}
.appbar {
  position: sticky;
  top: 0;
  background: var(--bg);
  padding: 8px 0;
  border-bottom: 1px solid rgba(15, 23, 42, 0.06);
  backdrop-filter: saturate(1.1) blur(6px);
  z-index: 10;
}
.install-hint {
  background: #fff7ed;
  border: 1px solid #fed7aa;
  color: #7c2d12;
  padding: 10px 12px;
  border-radius: 12px;
  font-size: 0.98rem;
  margin-bottom: 12px;
}