:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --success: #16a34a;
    --danger: #dc2626;
    --warning: #f59e0b;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--gray-100);
    color: var(--gray-800);
    line-height: 1.5;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header */
header {
    background: white;
    border-bottom: 1px solid var(--gray-200);
    padding: 1rem 0;
    margin-bottom: 2rem;
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

nav a {
    color: var(--gray-600);
    text-decoration: none;
    margin-left: 2rem;
    padding: 0.5rem 1rem;
    border-radius: 0.375rem;
    transition: all 0.2s;
}

nav a:hover, nav a.active {
    background: var(--primary);
    color: white;
}

/* Cards */
.card {
    background: white;
    border-radius: 0.5rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
}

.card h2 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: var(--gray-800);
}

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

label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--gray-700);
}

input[type="text"],
input[type="password"],
input[type="number"],
select,
textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--gray-300);
    border-radius: 0.375rem;
    font-size: 1rem;
    transition: border-color 0.2s;
}

input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.375rem;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.2s;
}

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

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

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

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

.btn-secondary {
    background: var(--gray-200);
    color: var(--gray-700);
}

/* Upload Area */
.upload-area {
    border: 2px dashed var(--gray-300);
    border-radius: 0.5rem;
    padding: 3rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
}

.upload-area:hover {
    border-color: var(--primary);
    background: var(--gray-50);
}

.upload-area.dragover {
    border-color: var(--primary);
    background: rgba(37, 99, 235, 0.05);
}

.upload-area input {
    display: none;
}

.upload-icon {
    font-size: 3rem;
    color: var(--gray-300);
    margin-bottom: 1rem;
}

/* Tables */
table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
}

th {
    background: var(--gray-50);
    font-weight: 600;
    color: var(--gray-700);
}

tr:hover {
    background: var(--gray-50);
}

/* Status badges */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.875rem;
    font-weight: 500;
}

.badge-success {
    background: #dcfce7;
    color: var(--success);
}

.badge-danger {
    background: #fee2e2;
    color: var(--danger);
}

.badge-warning {
    background: #fef3c7;
    color: var(--warning);
}

.badge-pending {
    background: var(--gray-200);
    color: var(--gray-600);
}

/* Alerts */
.alert {
    padding: 1rem;
    border-radius: 0.375rem;
    margin-bottom: 1rem;
}

.alert-success {
    background: #dcfce7;
    color: var(--success);
    border: 1px solid #bbf7d0;
}

.alert-danger {
    background: #fee2e2;
    color: var(--danger);
    border: 1px solid #fecaca;
}

.alert-warning {
    background: #fef3c7;
    color: #92400e;
    border: 1px solid #fde68a;
}

.alert-info {
    background: #dbeafe;
    color: #1e40af;
    border: 1px solid #bfdbfe;
}

/* Progress */
.progress {
    height: 0.5rem;
    background: var(--gray-200);
    border-radius: 9999px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: var(--primary);
    transition: width 0.3s;
}

/* Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.stat-card {
    background: white;
    border-radius: 0.5rem;
    padding: 1.5rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--gray-800);
}

.stat-label {
    color: var(--gray-600);
    font-size: 0.875rem;
}

/* Preview table */
.preview-container {
    max-height: 400px;
    overflow-y: auto;
    margin-top: 1rem;
}

/* Responsive */
@media (max-width: 768px) {
    header .container {
        flex-direction: column;
        gap: 1rem;
    }

    nav a {
        margin-left: 0;
        margin-right: 1rem;
    }
}

/* Loading spinner */
.spinner {
    display: inline-block;
    width: 1rem;
    height: 1rem;
    border: 2px solid var(--gray-300);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* Modal */
.modal-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 100;
    align-items: center;
    justify-content: center;
}

.modal-overlay.active {
    display: flex;
}

.modal {
    background: white;
    border-radius: 0.5rem;
    padding: 1.5rem;
    max-width: 500px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
}

.modal h3 {
    margin-bottom: 1rem;
}

/* Pagination */
.pagination {
    display: flex;
    gap: 0.5rem;
    justify-content: center;
    margin-top: 1.5rem;
}

.pagination a {
    padding: 0.5rem 1rem;
    border: 1px solid var(--gray-300);
    border-radius: 0.375rem;
    text-decoration: none;
    color: var(--gray-700);
}

.pagination a:hover, .pagination a.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}