body {
    font-family: 'Arial', sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
    color: #333;
}

header {
    background: linear-gradient(135deg, #4CAF50, #45a049);
    color: white;
    padding: 20px;
    text-align: center;
}

nav {
    background-color: #333;
    padding: 10px;
    text-align: center;
}

nav a {
    color: white;
    margin: 0 15px;
    text-decoration: none;
    font-weight: bold;
}

nav a:hover {
    text-decoration: underline;
}

.container {
    max-width: 1200px;
    margin: 20px auto;
    padding: 20px;
    background-color: white;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    border-radius: 10px;
}

h2 {
    color: #4CAF50;
    margin-top: 20px;
}

h3 {
    color: #4CAF50;
    margin-top: 15px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 20px;
}

table th, table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

table th {
    background-color: #4CAF50;
    color: white;
}

table tr:hover {
    background-color: #f1f1f1;
}

#backToTop {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: #4CAF50;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    display: none; /* ซ่อนปุ่มเริ่มต้น */
    transition: background-color 0.3s ease; /* เพิ่มเอฟเฟกต์เมื่อ hover */
}

#backToTop:hover {
    background-color: #45a049; /* เปลี่ยนสีเมื่อ hover */
}