body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    background: white;
    padding: 20px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    border-radius: 5px;
}

h1, h2, h3 {
    color: #333;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
}

.form-control {
    width: 100%;
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    box-sizing: border-box;
}

.btn {
    display: inline-block;
    padding: 10px 15px;
    background: #4CAF50;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
}

.btn:hover {
    background: #45a049;
}

.btn-danger {
    background: #f44336;
}

.btn-danger:hover {
    background: #d32f2f;
}

.alert {
    padding: 15px;
    margin-bottom: 20px;
    border: 1px solid transparent;
    border-radius: 4px;
}

.alert-success {
    color: #3c763d;
    background-color: #dff0d8;
    border-color: #d6e9c6;
}

.alert-danger {
    color: #a94442;
    background-color: #f2dede;
    border-color: #ebccd1;
}

.nav {
    margin-bottom: 20px;
    background: #333;
    padding: 10px;
    border-radius: 4px;
}

.nav a {
    color: white;
    margin-right: 15px;
    text-decoration: none;
}

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

.tab-content {
    display: none;
}

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

.hidden {
    display: none;
}