* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Microsoft YaHei", Arial, sans-serif;
  color: #111827;
  background:
    radial-gradient(circle at 18% 12%, rgba(255, 229, 59, .35), transparent 30%),
    linear-gradient(135deg, #fff7b0 0%, #f4f7fb 42%, #dff3ff 100%);
}

a {
  color: inherit;
}

.join-shell {
  width: min(960px, calc(100% - 28px));
  min-height: 100vh;
  margin: 0 auto;
  display: grid;
  align-items: center;
  padding: 28px 0;
}

.join-card {
  position: relative;
  overflow: hidden;
  border: 1px solid rgba(17, 24, 39, .12);
  border-radius: 8px;
  background: rgba(255, 255, 255, .94);
  box-shadow: 0 24px 70px rgba(17, 24, 39, .18);
}

.join-card::before {
  content: "";
  display: block;
  height: 10px;
  background: linear-gradient(90deg, #ffdd00, #ff7a00, #22c55e, #0284c7);
}

.back-link {
  position: absolute;
  top: 24px;
  right: 24px;
  padding: 8px 12px;
  border: 1px solid rgba(17, 24, 39, .14);
  border-radius: 6px;
  color: #374151;
  text-decoration: none;
  font-size: 14px;
  background: #fff;
}

.hero {
  padding: 44px 40px 22px;
}

.eyebrow {
  margin: 0 0 10px;
  color: #d97706;
  font-size: 14px;
  font-weight: 700;
}

h1 {
  margin: 0;
  max-width: 720px;
  font-size: 34px;
  line-height: 1.25;
}

.hero p:last-child {
  max-width: 680px;
  margin: 14px 0 0;
  color: #4b5563;
  line-height: 1.7;
}

.group-panel {
  display: grid;
  grid-template-columns: 72px minmax(0, 1fr) auto;
  gap: 14px;
  align-items: center;
  margin: 10px 40px 18px;
  padding: 18px;
  border: 2px solid #111827;
  border-radius: 8px;
  background: #fff200;
}

.group-panel span {
  font-weight: 700;
}

.group-panel strong {
  overflow-wrap: anywhere;
  font-size: 32px;
  letter-spacing: 0;
}

button,
.action-row a,
.empty-action {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 10px 16px;
  border: 0;
  border-radius: 6px;
  color: #fff;
  background: #1f2937;
  font: inherit;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
}

.copy-btn {
  color: #111827;
  background: #fff;
}

.action-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 0 40px 24px;
}

.action-row .primary {
  color: #111827;
  background: #22c55e;
}

.empty-action {
  grid-column: 1 / -1;
  color: #92400e;
  background: #fef3c7;
}

.manual-card {
  margin: 0 40px 24px;
  padding: 18px;
  border: 1px solid #bbf7d0;
  border-radius: 8px;
  background: #f0fdf4;
}

.manual-card h2 {
  margin: 0 0 10px;
  font-size: 18px;
}

.manual-card p {
  margin: 0;
  color: #166534;
  line-height: 1.7;
}

.manual-card p + p {
  margin-top: 8px;
}

.manual-card .warn {
  color: #854d0e;
}

body.copied .manual-card {
  border-color: #22c55e;
  box-shadow: inset 0 0 0 1px #22c55e;
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  margin: 0 40px 28px;
  overflow: hidden;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  background: #d1d5db;
}

.info-grid div {
  min-height: 86px;
  padding: 14px;
  background: #fff;
}

.info-grid span {
  display: block;
  margin-bottom: 8px;
  color: #6b7280;
  font-size: 13px;
}

.info-grid strong {
  display: block;
  overflow-wrap: anywhere;
  line-height: 1.45;
}

.tips {
  padding: 22px 40px 34px;
  border-top: 1px solid #e5e7eb;
  background: #f9fafb;
}

.tips h2 {
  margin: 0 0 8px;
  font-size: 18px;
}

.tips p {
  margin: 0;
  color: #4b5563;
  line-height: 1.7;
}

@media (max-width: 760px) {
  .back-link {
    position: static;
    display: inline-flex;
    margin: 18px 18px 0;
  }

  .hero,
  .tips {
    padding-left: 22px;
    padding-right: 22px;
  }

  h1 {
    font-size: 26px;
  }

  .group-panel,
  .manual-card,
  .action-row,
  .info-grid {
    grid-template-columns: 1fr;
    margin-left: 22px;
    margin-right: 22px;
  }

  .group-panel strong {
    font-size: 28px;
  }
}