* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Helvetica', sans-serif;
  }
  
  body {
    background: #f4f4f4;
    color: #333;
    line-height: 1.6;
  }
  
  header {
    background: #003366;
    color: #fff;
    padding: 1rem;
  }
  
  header h1 {
    margin-bottom: 0.5rem;
  }
  
  nav ul {
    list-style: none;
    display: flex;
    gap: 1rem;
  }
  
  nav a {
    color: #fff;
    text-decoration: none;
  }
  
  main {
    display: flex;
    width: 100%;
    margin: 2rem auto;
    padding: 1rem;
    gap: 2rem;
  }

  .contents {
    flex: 3;
    width: 80%;
  }

  .sidebar {
    flex: 1;
    background: #fff;
    width: 20%;
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 0 5px rgba(0,0,0,0);
  }
  
  footer {
    position: fixed;
    background: #036;
    color: #fff;
    text-align: center;
    width: 100%;
    height: 40px;
    bottom: 0;
    left: 0;
  }