:root {
  color: #111111;
  background: #f5f5f7;
  --zf-green: #19a447;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
}

* { box-sizing: border-box; }
html { min-width: 320px; background: #f5f5f7; -webkit-text-size-adjust: 100%; }
body { min-height: 100vh; margin: 0; background: #f5f5f7; }
a { color: inherit; }

.shell {
  width: min(100% - 40px, 860px);
  min-height: 100vh;
  margin: 0 auto;
  padding: max(14px, env(safe-area-inset-top)) 0 max(32px, env(safe-area-inset-bottom));
}

.topbar { display: flex; align-items: center; min-height: 46px; }
.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  color: #111111;
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  text-decoration: none;
}
.brand-mark { width: 38px; height: 38px; flex: 0 0 auto; }

.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: clamp(92px, 16vh, 150px) 20px 48px;
  text-align: center;
}
h1 { margin: 0; font-size: clamp(2.75rem, 8vw, 4.75rem); line-height: 1.08; letter-spacing: -0.055em; }
.intro { margin: 20px 0 36px; color: #6e6e73; font-size: 1.0625rem; line-height: 1.5; }

.download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: min(100%, 400px);
  min-height: 58px;
  padding: 14px 24px;
  border-radius: 18px;
  background: #111111;
  box-shadow: 0 7px 16px rgba(0, 0, 0, 0.10);
  color: #ffffff;
  font-size: 1.0625rem;
  font-weight: 650;
  text-decoration: none;
  transition: transform 160ms ease, opacity 160ms ease;
  -webkit-tap-highlight-color: transparent;
}
.download svg {
  width: 23px;
  margin-right: 10px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.8;
}
.download:hover { opacity: 0.9; }
.download:active { transform: scale(0.985); }
.download:focus-visible { outline: 3px solid color-mix(in srgb, var(--zf-green) 42%, transparent); outline-offset: 4px; }
.requirement { margin: 17px 0 0; color: #6e6e73; font-size: 0.875rem; }
.invite-card {
  display: grid;
  width: min(100%, 400px);
  margin: 0 0 28px;
  padding: 20px;
  gap: 10px;
  border: 1px solid rgba(60, 60, 67, 0.12);
  border-radius: 20px;
  background: #ffffff;
}
.invite-card[hidden] { display: none; }
.invite-card p, .invite-card span { margin: 0; color: #6e6e73; font-size: 0.875rem; }
.invite-card strong { font-size: 2rem; letter-spacing: 0.16em; }
.invite-card button {
  min-height: 46px;
  border: 0;
  border-radius: 14px;
  background: var(--zf-green);
  color: #ffffff;
  font: inherit;
  font-weight: 650;
  cursor: pointer;
}
.invite-card button:focus-visible { outline: 3px solid color-mix(in srgb, var(--zf-green) 42%, transparent); outline-offset: 3px; }

.features {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  overflow: hidden;
  border: 1px solid rgba(60, 60, 67, 0.12);
  border-radius: 24px;
  background: #ffffff;
  box-shadow: 0 7px 22px rgba(0, 0, 0, 0.035);
}
.features article {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  min-height: 132px;
  padding: 28px;
}
.features article + article::before {
  position: absolute;
  top: 24px;
  bottom: 24px;
  left: 0;
  width: 1px;
  background: rgba(60, 60, 67, 0.12);
  content: "";
}
.features span {
  display: grid;
  width: 48px;
  height: 48px;
  flex: 0 0 auto;
  place-items: center;
  border-radius: 50%;
  background: color-mix(in srgb, var(--zf-green) 9%, transparent);
  color: #111111;
  font-size: 1.125rem;
  font-weight: 700;
}
.features h2 { margin: 0; font-size: 1.0625rem; font-weight: 650; }
.features p { margin: 5px 0 0; color: #6e6e73; font-size: 0.875rem; }

@media (max-width: 560px) {
  .shell { width: min(100% - 32px, 860px); }
  .hero { padding: clamp(78px, 14vh, 116px) 0 42px; }
  .features article { gap: 12px; min-height: 118px; padding: 22px 12px; }
  .features span { width: 42px; height: 42px; }
}
@media (max-width: 380px) {
  .features article { flex-direction: column; gap: 10px; text-align: center; }
  .features article + article::before { top: 18px; bottom: 18px; }
}
@media (prefers-reduced-motion: reduce) { .download { transition: none; } }