:root {
    --primary-color: #007bff;
    --primary-hover: #0056b3;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --text-color: #333;
    --muted-text: #6c757d;
    --error-color: #dc3545;
    --success-color: #28a745;
    --border-color: #dee2e6;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    margin: 0;
    padding: 0;
}

.container {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

h1, h2, h3 {
    margin-top: 0;
}

.btn {
    display: inline-block;
    padding: 0.6rem 1.2rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
    border: none;
}

.btn-primary {
    background-color: var(--primary-color);
    color: #fff;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
}

.btn-danger {
    background-color: var(--error-color);
    color: #fff;
}

.btn-danger:hover {
    background-color: #bd2130;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.form-control {
    width: 100%;
    padding: 0.6rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    box-sizing: border-box;
    font-size: 1rem;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(0, 123, 255, 0.25);
}

.alert {
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
}

.alert-error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.alert-success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

th, td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: #f2f2f2;
    font-weight: 600;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.nav a {
    text-decoration: none;
    color: var(--primary-color);
}

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

.badge {
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.85rem;
    font-weight: 600;
}

.badge-active {
    background-color: var(--success-color);
    color: #fff;
}

.badge-pending {
    background-color: var(--muted-text);
    color: #fff;
}

@media (max-width: 768px) {
    .container {
        margin: 1rem auto;
        padding: 0 0.75rem;
    }
    .card {
        padding: 1.25rem;
    }
    .nav {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }
    .nav h1 {
        margin-bottom: 0;
    }
    table {
        display: block;
        width: 100%;
    }
    thead {
        display: none;
    }
    tr {
        display: block;
        padding: 1rem 0;
        border-bottom: 2px solid var(--border-color);
    }
    td {
        display: block;
        padding: 0.5rem 0;
        text-align: right;
        border: none;
    }
    td::before {
        content: attr(data-label);
        float: left;
        font-weight: 600;
        color: var(--muted-text);
    }
    td:last-child {
        text-align: center;
        margin-top: 1rem;
    }
}