* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  color: #1a1a2e;
  background: #f8f9fc;
  line-height: 1.5;
}
a { color: #512da8; }
.lang-switcher {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
  flex-wrap: wrap;
  padding: 12px 20px;
  background: #fff;
  border-bottom: 1px solid #e8eaf0;
  position: sticky;
  top: 0;
  z-index: 10;
}
.lang-link {
  text-decoration: none;
  font-size: 0.85rem;
  padding: 4px 10px;
  border-radius: 6px;
  color: #555;
}
.lang-link.lang-active,
.lang-link:hover {
  background: #ede7f6;
  color: #512da8;
  font-weight: 600;
}
.hero {
  background: linear-gradient(145deg, #1a237e 0%, #512da8 55%, #7b1fa2 100%);
  color: #fff;
  padding: 48px 24px 64px;
  text-align: center;
}
.hero h1 { font-size: clamp(1.75rem, 5vw, 2.5rem); margin: 0 0 16px; }
.hero p { max-width: 520px; margin: 0 auto 28px; opacity: 0.92; font-size: 1.05rem; }
.btn-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-block;
  padding: 14px 28px;
  border-radius: 12px;
  font-weight: 600;
  text-decoration: none;
  font-size: 1rem;
}
.btn-primary { background: #fff; color: #512da8; }
.btn-outline { border: 2px solid rgba(255,255,255,0.7); color: #fff; }
.features {
  max-width: 960px;
  margin: -32px auto 48px;
  padding: 0 20px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.feature-card {
  background: #fff;
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.06);
}
.feature-card h3 { margin: 0 0 8px; color: #512da8; }
.feature-card p { margin: 0; color: #555; font-size: 0.95rem; }
footer {
  text-align: center;
  padding: 32px 20px 48px;
  color: #777;
  font-size: 0.9rem;
  border-top: 1px solid #e8eaf0;
}
footer p { max-width: 560px; margin: 8px auto; }

/* Invite page */
body.invite-page {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: linear-gradient(145deg, #1a237e 0%, #512da8 50%, #7b1fa2 100%);
  color: #fff;
}
.invite-page .lang-switcher { background: rgba(0,0,0,0.15); border: none; }
.invite-page .lang-link { color: rgba(255,255,255,0.85); }
.invite-page .lang-link.lang-active,
.invite-page .lang-link:hover { background: rgba(255,255,255,0.2); color: #fff; }
.invite-wrap {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}
.invite-card {
  background: rgba(255,255,255,0.12);
  backdrop-filter: blur(12px);
  border-radius: 20px;
  padding: 32px 28px;
  max-width: 420px;
  width: 100%;
  text-align: center;
  box-shadow: 0 16px 48px rgba(0,0,0,0.25);
}
.invite-card h1 { font-size: 1.5rem; margin: 0 0 8px; }
.invite-card .subtitle { opacity: 0.9; margin-bottom: 24px; }
.code-box {
  background: rgba(0,0,0,0.25);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 24px;
}
.code-label { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.08em; opacity: 0.8; }
.code-value { font-size: 2rem; font-weight: 800; letter-spacing: 0.2em; margin-top: 8px; font-family: ui-monospace, monospace; }
.invite-card .btn {
  display: block;
  width: 100%;
  margin-bottom: 12px;
  border: none;
  cursor: pointer;
  text-align: center;
}
.invite-card .btn-primary { background: #fff; color: #512da8; }
.invite-card .btn-secondary {
  background: transparent;
  color: #fff;
  border: 2px solid rgba(255,255,255,0.5);
}
.invite-card .hint { font-size: 0.8rem; opacity: 0.75; margin-top: 16px; }
.invite-card .error { color: #ffcdd2; }