body {
    font-family: Arial, sans-serif;
    background: #f5f5f5;
    margin: 0;
    padding: 0;
}
header {
    background-color: #333;
    padding: 10px 0;
}
nav ul.menu {
    list-style-type: none;
    margin: 0;
    padding: 0;
    text-align: center;
}
nav ul.menu li {
    display: inline;
    margin: 0 15px;
}
nav ul.menu li a {
    color: white;
    text-decoration: none;
    font-size: 18px;
}
nav ul.menu li a:hover {
    text-decoration: underline;
}
main {
    padding: 20px;
}
h1, h2 {
    color: #333;
}
table {
    width: 100%;
    background: white;
    border-collapse: collapse;
    margin-bottom: 30px;
}
th, td {
    padding: 10px;
    border: 1px solid #ccc;
    text-align: left;
}
tr:hover {
    background-color: #f1f1f1;
}
form {
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px #ccc;
    margin-bottom: 30px;
}
input[type="text"], input[type="number"], select {
    width: 100%;
    padding: 8px;
    margin-bottom: 10px;
}
input[type="submit"], button {
    background-color: #333;
    color: white;
    border: none;
    padding: 10px 20px;
    cursor: pointer;
}
input[type="submit"]:hover, button:hover {
    background-color: #555;
}
.success {
    color: green;
    margin-bottom: 10px;
}
.error {
    color: red;
    margin-bottom: 10px;
}