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

body {
  font-family: "Hiragino Sans", "Yu Gothic", sans-serif;
  line-height: 1.7;
  color: #222;
  background: #fafafa;
}

header {
  padding: 2rem 1.5rem;
  border-bottom: 1px solid #ddd;
}

header h1 {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

nav a {
  margin-right: 1.5rem;
  text-decoration: none;
  color: #333;
}

nav a:hover {
  text-decoration: underline;
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
}

section {
  margin-bottom: 3rem;
}

section h2 {
  font-size: 1.2rem;
  margin-bottom: 1rem;
  border-left: 4px solid #333;
  padding-left: 0.5rem;
}

footer {
  text-align: center;
  padding: 1.5rem;
  font-size: 0.85rem;
  color: #777;
}