* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: Arial, sans-serif;
  background: #f5f6fa;
  color: #222;
  line-height: 1.7;
}

.container {
  width: 92%;
  max-width: 1100px;
  margin: 0 auto;
}

.site-header {
  background: #ffffff;
  border-bottom: 1px solid #e5e7eb;
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 0;
}

.logo {
  font-size: 28px;
  font-weight: bold;
  color: #111827;
}

.logo span {
  color: #2563eb;
}

.nav a {
  margin-left: 18px;
  text-decoration: none;
  color: #333;
  font-weight: 500;
}

.nav a:hover {
  color: #2563eb;
}

.hero {
  background: linear-gradient(135deg, #2563eb, #38bdf8);
  color: white;
  padding: 60px 0;
  text-align: center;
}

.hero h1 {
  font-size: 42px;
  margin-bottom: 12px;
}

.hero p {
  font-size: 18px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
  margin: 30px 0;
}

.card {
  background: #fff;
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.06);
}

.card h3 {
  margin-bottom: 10px;
}

.card a {
  color: #111827;
  text-decoration: none;
}

.card a:hover {
  color: #2563eb;
}

.article {
  max-width: 780px;
  background: #ffffff;
  margin-top: 30px;
  margin-bottom: 30px;
  padding: 32px;
  border-radius: 16px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.05);
}

.article h1 {
  font-size: 36px;
  line-height: 1.25;
  margin-bottom: 18px;
  color: #111827;
}

.article h2 {
  font-size: 24px;
  margin-top: 28px;
  margin-bottom: 10px;
  color: #1f2937;
}

.article p {
  margin: 12px 0;
  font-size: 17px;
}

.article ul {
  margin: 12px 0 12px 22px;
}

.related {
  margin-top: 40px;
  padding: 22px;
  background: #eef2ff;
  border-radius: 14px;
  border-left: 5px solid #2563eb;
}

.related h3 {
  margin-bottom: 12px;
  font-size: 22px;
}

.related ul {
  padding-left: 18px;
}

.related li {
  margin: 7px 0;
}

.related a {
  color: #2563eb;
  text-decoration: none;
  font-weight: 500;
}

.related a:hover {
  text-decoration: underline;
}

.footer {
  background: #111827;
  color: white;
  text-align: center;
  padding: 25px 0;
  margin-top: 40px;
}

@media (max-width: 800px) {
  .header-inner {
    flex-direction: column;
    gap: 12px;
  }

  .nav {
    text-align: center;
  }

  .nav a {
    display: inline-block;
    margin: 6px;
  }

  .hero h1 {
    font-size: 32px;
  }

  .grid {
    grid-template-columns: 1fr;
  }

  .article {
    padding: 22px;
  }

  .article h1 {
    font-size: 30px;
  }
}