body {
  font-family: "Segoe UI","Hiragino Sans","Yu Gothic",sans-serif;
  margin: 40px;
  line-height: 1.75;
  color: #222;
}
header {
  border-bottom: 3px solid #444;
  margin-bottom: 24px;
}
nav {
  margin-bottom: 32px;
}
nav ul { list-style: none; padding-left: 0; }
nav li { margin: 6px 0; }
nav ul ul { margin-left: 20px; }
a { color: #0066aa; text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3 { color: #333; }
code { background: #f4f4f4; padding: 2px 4px; }
footer {
  margin-top: 60px;
  padding-top: 12px;
  border-top: 1px solid #ccc;
  color: #666;
}