body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f9;
}
header {
    background-color: #4caf50;
    color: white;
    text-align: center;
    padding: 1rem 0;
}
nav {
    background-color: #333;
    overflow: hidden;
}
nav a {
    float: left;
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}
nav a:hover {
    background-color: #ddd;
    color: black;
}
.container {
    padding: 20px;
}
.course {
    background: white;
    margin: 20px 0;
    padding: 20px;
    border: 1px solid #ddd;
    border-radius: 8px;
}
.course h3 {
    margin-top: 0;
}
button {
    background-color: #4caf50;
    color: white;
    border: none;
    padding: 10px 15px;
    cursor: pointer;
    border-radius: 5px;
}
button:hover {
    background-color: #45a049;
}
footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 10px 0;
    position: relative;
    bottom: 0;
    width: 100%;
}