* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  html, body {
    height: 100%;
  }
  
  body {
    font-family: Arial, sans-serif;
  }
  
  #header {
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
  }
  
  #header h1 {
    margin: 0;
    font-size: 32px;
  }
  
  #nav {
    background-color: #000;
    color: #fff;
    padding: 10px;
  }
  
  #nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
  }
  
  #nav li {
    margin-right: 20px;
  }
  
  #nav a {
    color: #fff;
    text-decoration: none;
  }
  
  #nav a:hover {
    text-decoration: underline;
  }

  #nav a.active, #sidebar a.active {
  font-weight: bold;
  text-decoration: underline;
}
  
  #content {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    margin: 20px;

  }
  
  #sidebar {
    width: 20%;
    padding: 20px;
  }
  
  #sidebar h2 {
    color: #333;
  }
  
  #sidebar ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
  }
  
  #sidebar li {
    margin-bottom: 10px;
  }
  
  #sidebar a {
    color: #000;
    text-decoration: none;
  }
  
  #sidebar a:hover {
    text-decoration: underline;
  }
  
  #main {
    width: 60%;
    padding: 20px;
  }
  
  #sidebar2 {
    width: 20%;
    padding: 20px;
   
  }
  
  #footer {
    background-color: #333;
    color: #fff;
    padding: 20px;
    text-align: center;
    border-top: 2px solid #000;
  }