body {
  font-family: 'Open Sans', Arial, sans-serif;
  background: #f8f9fa;
  color: #333;
  margin: 0;
  padding: 0;
}

.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: 220px;
  height: 100vh;
  background: #fff;
  border-right: 1px solid #dadada;
  box-shadow: 2px 0 8px rgba(0,0,0,0.07);
  padding: 28px 16px 28px 24px;
  box-sizing: border-box;
  z-index: 10;
}

.sidebar h2 {
  color: #667eea;
  font-size: 23px;
  font-weight: 700;
  margin-bottom: 24px;
  letter-spacing: 0.02em;
}

.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.sidebar ul li {
  margin-bottom: 12px;
}

.sidebar ul li a {
  display: block;
  padding: 8px 14px;
  color: #4a4a4a;
  text-decoration: none;
  font-weight: 600;
  border-radius: 5px;
  transition: background 0.2s, color 0.2s;
}

.sidebar ul li a.active,
.sidebar ul li a:hover {
  background: #667eea;
  color: #fff;
}

main {
  margin-left: 240px;
  padding: 40px;
  max-width: 950px;
}

header h1 {
  font-size: 34px;
  font-weight: 700;
  color: #222;
  margin-bottom: 14px;
}

header p {
  font-size: 19px;
  color: #616161;
  margin-top: 0;
  margin-bottom: 28px;
}

section h2 {
  font-size: 24px;
  color: #667eea;
  border-bottom: 2px solid #ececec;
  padding-bottom: 5px;
  margin-bottom: 18px;
}
ul, ol {
  font-size: 16px;
  color: #444;
  margin-left: 20px;
}
p {
  font-size: 16px;
  line-height: 1.6;
}
code {
  background: #eef2fb;
  padding: 3px 6px;
  font-size: 15px;
  border-radius: 4px;
  font-family: 'Menlo', monospace;
  color: #26357b;
}
table {
  border-collapse: collapse;
  margin: 16px 0; width: 100%;
}
th, td {
  padding: 10px 14px;
  border: 1px solid #d4d8e5;
  font-size: 15px;
}
th {
  background: #667eea;
  color: #fff;
}
button {
  background: #667eea;
  border: none;
  color: #fff;
  padding: 8px 16px;
  font-size: 16px;
  border-radius: 4px;
  cursor: pointer;
  margin-top: 8px;
  transition: background 0.2s;
}
button:hover {
  background: #556cd6;
}
@media (max-width: 900px) {
  .sidebar { position: relative; width: 100%; height: auto; box-shadow: none; border-right: none; }
  main { margin-left: 0; padding: 16px; max-width: 100%; }
}