:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --border-color: #334155;
    --success-color: #10b981;
    --error-color: #ef4444;
    --font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --radius-lg: 16px;
    --radius-md: 8px;
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --transition: all 0.3s ease;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 2rem;
}

.app-container {
    width: 100%;
    max-width: 1600px;
    padding: 0 2rem;
}

.app-header {
    text-align: center;
    margin-bottom: 3rem;
    animation: fadeInDown 0.8s ease-out;
}

.app-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, #60a5fa, #a78bfa);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

.app-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.card {
    background-color: var(--card-bg);
    border-radius: var(--radius-lg);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    animation: fadeInUp 0.5s ease-out forwards;
    opacity: 0;
    transform: translateY(20px);
}

.card:nth-child(1) { animation-delay: 0.1s; }
.card:nth-child(2) { animation-delay: 0.2s; }
.card:nth-child(3) { animation-delay: 0.3s; }

.hidden {
    display: none !important;
}

.step-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

.step-number {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 32px;
    height: 32px;
    background-color: var(--primary-color);
    color: white;
    border-radius: 50%;
    font-weight: 600;
}

.step-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
}

/* Upload Grid */
.upload-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .upload-grid {
        grid-template-columns: 1fr;
    }
}

.upload-zone {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-md);
    padding: 2rem 1rem;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background-color: rgba(15, 23, 42, 0.5);
}

.upload-zone:hover, .upload-zone.dragover {
    border-color: var(--primary-color);
    background-color: rgba(59, 130, 246, 0.1);
    transform: translateY(-2px);
}

.upload-icon {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.upload-zone h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}

.upload-zone p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.file-name {
    margin-top: 1rem;
    font-size: 0.85rem;
    color: var(--success-color);
    font-weight: 500;
    word-break: break-all;
}

/* Mapping UI */
.mapping-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

@media (max-width: 768px) {
    .mapping-container {
        grid-template-columns: 1fr;
    }
}

.mapping-group {
    background-color: rgba(15, 23, 42, 0.5);
    padding: 1.5rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.mapping-group h3 {
    margin-bottom: 1rem;
    font-size: 1.1rem;
    color: var(--primary-color);
}

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.form-group select, .form-group input {
    width: 100%;
    padding: 0.75rem;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-family);
    transition: var(--transition);
    outline: none;
}

.form-group select:focus, .form-group input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
}

.checkbox-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    max-height: 200px;
    overflow-y: auto;
    padding: 0.5rem;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
}

.checkbox-group::-webkit-scrollbar {
    width: 6px;
}
.checkbox-group::-webkit-scrollbar-thumb {
    background-color: var(--border-color);
    border-radius: 10px;
}

.checkbox-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.checkbox-item input[type="checkbox"] {
    accent-color: var(--primary-color);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
    border: none;
    outline: none;
    width: 100%;
}

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

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.btn-secondary {
    background-color: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

.actions {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 1rem;
    margin-top: 1.5rem;
}

/* Table Preview */
.results-stats {
    margin-bottom: 1rem;
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.table-container {
    overflow-x: auto;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
}

table {
    width: 100%;
    border-collapse: collapse;
}

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

th {
    background-color: rgba(15, 23, 42, 0.8);
    font-weight: 600;
    color: var(--primary-color);
    position: sticky;
    top: 0;
}

tbody tr:hover {
    background-color: rgba(255, 255, 255, 0.02);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.highlight-yellow {
    background-color: rgba(234, 179, 8, 0.2) !important;
}

.highlight-red {
    background-color: rgba(239, 68, 68, 0.2) !important;
}

/* CSP Compliant Classes */
.loading-indicator {
    text-align: center;
    margin-top: 2rem;
    color: var(--primary-color);
}

.legend {
    margin-bottom: 1rem;
    display: flex;
    gap: 1rem;
    font-size: 0.9rem;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.legend-swatch {
    display: inline-block;
    width: 12px;
    height: 12px;
    border-radius: 2px;
}

.swatch-yellow {
    background-color: rgba(234, 179, 8, 0.2);
    border: 1px solid #eab308;
}

.swatch-red {
    background-color: rgba(239, 68, 68, 0.2);
    border: 1px solid #ef4444;
}

.app-footer {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 2rem;
    padding-bottom: 2rem;
    line-height: 1.4;
}