body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0; 
    color: green;
  }
  
  header {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 1rem;
  }
  
  header h1 {
    font-size: 2.5rem;
  }
  
  header h2 {
    font-size: 1.5rem;
  }
  
  main {
    padding: 2rem;
  }
  
  h3 {
    font-size: 1.8rem;
    border-bottom: 2px solid #333;
    padding-bottom: 0.5rem;
    margin-bottom: 1rem;
  }
  
  p {
    margin-bottom: 1rem;
  }
  
  ul, ol {
    margin-left: 2rem;
  }
  
  .course {
    border: 1px solid #ccc;
    padding: 1rem;
    margin-bottom: 1rem;
  }
  
  .course h4 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
  }
  
  footer {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 1rem;
  }
  
  body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: rgb(0, 191, 255);
}

header {
    background-color: rgb(0, 0, 255);
    color: #fff;
    padding: 10px;
}

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

nav li {
    display: inline-block;
    margin-right: 20px;
}

nav a {
    color: #fff;
    text-decoration: none;
}

main {
    padding: 20px;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

h1 {
    color: #333;
    margin-bottom: 20px;
}

footer {
    background-color: rgb(0, 0, 255);
    color: #fff;
    text-align: center;
    padding: 10px;
}