:root {
  color-scheme: light;
  font-family: 'Helvetica Neue', Arial, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft Yahei', sans-serif;
}

body {
  margin: 0;
  background: #f8fafc;
  color: #1f2937;
  line-height: 1.7;
}

a {
  color: #4f46e5;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

header {
  background: linear-gradient(135deg, #4f46e5, #7c3aed);
  color: #fff;
  padding: 48px 20px 56px;
  text-align: center;
}

header h1 {
  margin: 0;
  font-size: 2.25rem;
  font-weight: 600;
}

header p {
  margin: 12px auto 0;
  max-width: 720px;
  font-size: 1.05rem;
  opacity: 0.92;
}

main {
  max-width: 900px;
  margin: -40px auto 60px;
  background: #fff;
  border-radius: 20px;
  padding: 40px 32px 48px;
  box-shadow: 0 16px 35px rgba(79, 70, 229, 0.12);
}

main h2 {
  font-size: 1.6rem;
  margin-top: 32px;
  color: #4338ca;
}

main h3 {
  font-size: 1.25rem;
  margin-top: 24px;
  color: #1d4ed8;
}

main p {
  margin: 12px 0;
}

main ul {
  margin: 16px 0 0 0;
  padding-left: 22px;
}

main li {
  margin-bottom: 10px;
}

footer {
  text-align: center;
  font-size: 0.85rem;
  color: #6b7280;
  margin-bottom: 40px;
}

@media (max-width: 640px) {
  header {
    padding: 36px 16px 44px;
  }

  header h1 {
    font-size: 1.8rem;
  }

  main {
    margin: -32px 16px 48px;
    padding: 32px 22px 36px;
    border-radius: 16px;
  }

  main h2 {
    font-size: 1.35rem;
  }
}