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

:root {
    --primary-color: #3b82f6;
    --primary-dark: #1e40af;
    --success-color: #10b981;
    --error-color: #ef4444;
    --bg-color: #f9fafb;
    --card-bg: #ffffff;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    color: var(--text-primary);
}

.container {
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
    max-width: 900px;
    width: 100%;
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 40px 20px;
    text-align: center;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 8px;
    font-weight: 700;
}

.subtitle {
    font-size: 1rem;
    opacity: 0.95;
    max-width: 500px;
    margin: 0 auto;
}

main {
    padding: 40px 20px;
}

.upload-section {
    margin-bottom: 40px;
}

.upload-box {
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 40px 20px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--bg-color);
    position: relative;
}

.upload-box:hover {
    border-color: var(--primary-color);
    background: #f0f7ff;
}

.upload-box.dragover {
    border-color: var(--primary-color);
    background: #f0f7ff;
    transform: scale(1.02);
}

.upload-icon {
    width: 48px;
    height: 48px;
    color: var(--primary-color);
    margin-bottom: 16px;
    display: inline-block;
}

.upload-box h3 {
    font-size: 1.25rem;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.upload-box p {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

#fileInput {
    display: none;
}

.results-section {
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 32px;
}

.stat-card {
    background: var(--bg-color);
    border-radius: 8px;
    padding: 20px;
    border-left: 4px solid var(--primary-color);
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

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

.preview-section {
    background: var(--bg-color);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}

.preview-header h3 {
    font-size: 1rem;
    color: var(--text-primary);
}

.btn-icon {
    background: none;
    border: none;
    font-size: 1.25rem;
    cursor: pointer;
    padding: 4px 8px;
    border-radius: 4px;
    transition: background 0.2s ease;
}

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

pre {
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 16px;
    overflow-x: auto;
    font-size: 0.875rem;
    line-height: 1.5;
    max-height: 400px;
    color: var(--text-primary);
    font-family: 'Menlo', 'Monaco', 'Courier New', monospace;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn-download {
    background: var(--success-color);
    color: white;
    width: 100%;
    justify-content: center;
}

.btn-download:hover {
    background: #059669;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3);
}

.btn-download:active {
    transform: translateY(0);
}

.loading-spinner {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 16px;
    padding: 40px;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

.error-message {
    background: #fee2e2;
    border: 1px solid #fca5a5;
    color: #991b1b;
    padding: 16px;
    border-radius: 6px;
    margin-top: 16px;
    animation: slideIn 0.3s ease;
}

footer {
    background: var(--bg-color);
    border-top: 1px solid var(--border-color);
    padding: 20px;
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    main {
        padding: 20px;
    }

    .upload-box {
        padding: 30px 16px;
    }

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

    .preview-section {
        padding: 16px;
    }

    pre {
        font-size: 0.75rem;
        padding: 12px;
    }
}