:root {
    --primary-color: #0066cc;
    --primary-dark: #0052a3;
    --primary-light: #e6f2ff;
    --secondary-color: #6c757d;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --text-dark: #2c3e50;
    --text-light: #6c757d;
    --border-color: #dee2e6;
    --shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 1rem 3rem rgba(0, 0, 0, 0.175);
    --transition: all 0.3s ease-in-out;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--light-bg);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    color: var(--text-dark);
    font-weight: 600;
    margin-bottom: 1rem;
    line-height: 1.3;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.1rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: 1rem;
    color: var(--text-light);
}

/* Layout */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

.row {
    display: flex;
    flex-wrap: wrap;
    margin: -15px;
}

.col {
    padding: 15px;
    flex: 1 1 100%;
    min-width: 0;
}

.col-1 { flex: 0 0 8.333%; }
.col-2 { flex: 0 0 16.666%; }
.col-3 { flex: 0 0 25%; }
.col-4 { flex: 0 0 33.333%; }
.col-5 { flex: 0 0 41.666%; }
.col-6 { flex: 0 0 50%; }
.col-7 { flex: 0 0 58.333%; }
.col-8 { flex: 0 0 66.666%; }
.col-9 { flex: 0 0 75%; }
.col-10 { flex: 0 0 83.333%; }
.col-11 { flex: 0 0 91.666%; }
.col-12 { flex: 0 0 100%; }

@media (max-width: 768px) {
    .col-md-6 { flex: 0 0 50%; }
    .col-md-12 { flex: 0 0 100%; }
    h1 { font-size: 1.75rem; }
    h2 { font-size: 1.5rem; }
}

@media (max-width: 576px) {
    .col { padding: 10px; }
    .row { margin: -10px; }
    h1 { font-size: 1.5rem; }
    h2 { font-size: 1.25rem; }
}

/* Navigation */
.navbar {
    background-color: var(--white);
    box-shadow: var(--shadow);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.navbar-nav {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.navbar-nav a {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

.navbar-nav a:hover {
    color: var(--primary-color);
}

.navbar-nav .active a {
    color: var(--primary-color);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: 2px solid transparent;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: var(--transition);
    text-align: center;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background-color: var(--secondary-color);
    color: var(--white);
}

.btn-secondary:hover {
    background-color: #5a6268;
}

.btn-success {
    background-color: var(--success-color);
    color: var(--white);
}

.btn-success:hover {
    background-color: #218838;
}

.btn-danger {
    background-color: var(--danger-color);
    color: var(--white);
}

.btn-danger:hover {
    background-color: #c82333;
}

.btn-outline {
    background-color: transparent;
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.btn-block {
    width: 100%;
    display: block;
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.9rem;
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-dark);
}

.form-control {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    font-size: 1rem;
    font-family: inherit;
    transition: var(--transition);
}

.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(0, 102, 204, 0.1);
}

.form-control::placeholder {
    color: var(--text-light);
}

textarea.form-control {
    resize: vertical;
    min-height: 120px;
}

select.form-control {
    cursor: pointer;
}

.form-check {
    display: flex;
    align-items: center;
    margin-bottom: 1rem;
}

.form-check input[type="checkbox"],
.form-check input[type="radio"] {
    margin-right: 0.5rem;
    cursor: pointer;
    width: 18px;
    height: 18px;
}

.form-check label {
    margin-bottom: 0;
    cursor: pointer;
    font-weight: 400;
}

.form-error {
    color: var(--danger-color);
    font-size: 0.85rem;
    margin-top: 0.25rem;
    display: none;
}

.form-control.is-invalid,
.form-control.error {
    border-color: var(--danger-color);
}

.form-control.is-invalid ~ .form-error,
.form-control.error ~ .form-error {
    display: block;
}

.form-success {
    color: var(--success-color);
}

/* Cards */
.card {
    background-color: var(--white);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    box-shadow: 0 0.125rem 0.25rem rgba(0, 0, 0, 0.075);
    overflow: hidden;
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.card-header {
    padding: 1.5rem;
    background-color: var(--light-bg);
    border-bottom: 1px solid var(--border-color);
    font-weight: 600;
}

.card-body {
    padding: 1.5rem;
}

.card-footer {
    padding: 1.5rem;
    background-color: var(--light-bg);
    border-top: 1px solid var(--border-color);
}

/* Alerts */
.alert {
    padding: 1rem;
    margin-bottom: 1rem;
    border: 1px solid;
    border-radius: 0.5rem;
    display: flex;
    gap: 1rem;
}

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

.alert-danger {
    background-color: #f8d7da;
    border-color: #f5c6cb;
    color: #721c24;
}

.alert-warning {
    background-color: #fff3cd;
    border-color: #ffeeba;
    color: #856404;
}

.alert-info {
    background-color: #d1ecf1;
    border-color: #bee5eb;
    color: #0c5460;
}

.alert-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: inherit;
    opacity: 0.7;
    transition: var(--transition);
}

.alert-close:hover {
    opacity: 1;
}

/* Tables */
.table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1rem;
}

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

.table th {
    background-color: var(--light-bg);
    font-weight: 600;
    color: var(--text-dark);
}

.table tbody tr:hover {
    background-color: var(--light-bg);
}

.table-striped tbody tr:nth-child(odd) {
    background-color: rgba(0, 0, 0, 0.02);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: var(--white);
    padding: 0;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-lg);
    max-width: 500px;
    width: 90%;
    animation: slideIn 0.3s ease-out;
}

.modal-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-light);
}

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

@keyframes slideIn {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
    padding: 6rem 0;
    text-align: center;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--white);
}

.hero p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    color: rgba(255, 255, 255, 0.9);
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

/* Features Grid */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.feature-item {
    text-align: center;
    padding: 2rem 1rem;
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.feature-item h3 {
    margin-bottom: 0.5rem;
}

.feature-item p {
    font-size: 0.9rem;
}

/* Loading Spinner */
.spinner {
    display: inline-block;
    width: 40px;
    height: 40px;
    border: 4px solid var(--light-bg);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.spinner-small {
    width: 20px;
    height: 20px;
    border-width: 2px;
}

.text-center { text-align: center; }
.text-right { text-align: right; }
.text-left { text-align: left; }

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }
.mt-5 { margin-top: 3rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }
.mb-5 { margin-bottom: 3rem; }

.p-1 { padding: 0.5rem; }
.p-2 { padding: 1rem; }
.p-3 { padding: 1.5rem; }
.p-4 { padding: 2rem; }
.p-5 { padding: 3rem; }

.text-primary { color: var(--primary-color); }
.text-success { color: var(--success-color); }
.text-danger { color: var(--danger-color); }
.text-warning { color: var(--warning-color); }
.text-muted { color: var(--text-light); }

.bg-primary { background-color: var(--primary-color); color: var(--white); }
.bg-light { background-color: var(--light-bg); }
.bg-white { background-color: var(--white); }

.d-flex { display: flex; }
.flex-center { justify-content: center; align-items: center; }
.gap-1 { gap: 0.5rem; }
.gap-2 { gap: 1rem; }
.gap-3 { gap: 1.5rem; }

.border { border: 1px solid var(--border-color); }
.rounded { border-radius: 0.5rem; }

/* Footer */
footer {
    background-color: var(--text-dark);
    color: var(--white);
    padding: 3rem 0;
    margin-top: 5rem;
}

footer a {
    color: var(--white);
    text-decoration: none;
    transition: var(--transition);
}

footer a:hover {
    color: var(--primary-light);
}

.footer-content {
    margin-bottom: 2rem;
}

.footer-section h4 {
    color: var(--white);
    margin-bottom: 1rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 2rem;
    text-align: center;
    color: rgba(255, 255, 255, 0.7);
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar-nav {
        gap: 1rem;
    }

    .hero {
        padding: 4rem 0;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .features {
        grid-template-columns: 1fr;
    }

    .modal-content {
        width: 95%;
    }
}

@media (max-width: 576px) {
    .navbar {
        padding: 0.5rem 0;
    }

    .btn {
        padding: 0.5rem 1rem;
        font-size: 0.9rem;
    }

    .hero-actions {
        flex-direction: column;
    }

    .hero-actions .btn {
        width: 100%;
    }

    .table {
        font-size: 0.9rem;
    }

    .table th,
    .table td {
        padding: 0.5rem;
    }

    .col-6 { flex: 0 0 100%; }
}