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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo", sans-serif;
  line-height: 1.8;
  color: #1a1a1a;
  background: #fafafa;
  padding: 40px 20px;
  max-width: 800px;
  margin: 0 auto;
}

h1 {
  font-size: 28px;
  font-weight: 700;
  color: #111;
  margin-bottom: 8px;
  padding-bottom: 16px;
  border-bottom: 2px solid #0066cc;
}

.subtitle {
  color: #666;
  font-size: 14px;
  margin-bottom: 32px;
}

h2 {
  font-size: 20px;
  font-weight: 600;
  color: #111;
  margin-top: 40px;
  margin-bottom: 16px;
  padding-left: 12px;
  border-left: 4px solid #0066cc;
}

h3 {
  font-size: 16px;
  font-weight: 600;
  color: #333;
  margin-top: 24px;
  margin-bottom: 12px;
}

p {
  margin-bottom: 16px;
  font-size: 15px;
}

ul, ol {
  margin-bottom: 16px;
  padding-left: 24px;
}

li {
  margin-bottom: 8px;
  font-size: 15px;
}

strong {
  font-weight: 600;
  color: #111;
}

a {
  color: #0066cc;
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.highlight-box {
  background: #f0f7ff;
  border: 1px solid #b3d7ff;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
}

.highlight-box h3 {
  margin-top: 0;
  color: #0066cc;
}

.warning-box {
  background: #fff8e1;
  border: 1px solid #ffd54f;
  border-radius: 8px;
  padding: 20px;
  margin: 20px 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 14px;
}

th, td {
  border: 1px solid #ddd;
  padding: 12px;
  text-align: left;
}

th {
  background: #f5f5f5;
  font-weight: 600;
}

.footer {
  margin-top: 60px;
  padding-top: 24px;
  border-top: 1px solid #e0e0e0;
  color: #888;
  font-size: 13px;
  text-align: center;
}

.nav-link {
  display: inline-block;
  margin-bottom: 24px;
  color: #666;
  font-size: 14px;
}

.nav-link::before {
  content: "← ";
}

@media (max-width: 600px) {
  body {
    padding: 20px 16px;
  }

  h1 {
    font-size: 24px;
  }

  h2 {
    font-size: 18px;
  }
}