/* Professional Design System */
:root {
    /* Colors - Professional Palette */
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --success: #059669;
    --success-dark: #047857;
    --danger: #dc2626;
    --danger-light: #ef4444;

    --background: #ffffff;
    --background-secondary: #f8fafc;
    --background-tertiary: #f1f5f9;
    --surface: #ffffff;
    --surface-hover: #f8fafc;

    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;

    --border: #e2e8f0;
    --border-light: #f1f5f9;

    /* Shadows - Subtle & Professional */
    --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-full: 9999px;

    /* Transitions */
    --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset & Base */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    background: var(--background-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.background-gradient {
    display: none;
}

/* Container */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing-2xl) var(--spacing-lg);
}

/* Header */
.header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.logo {
    display: inline-block;
    margin-bottom: var(--spacing-lg);
}

.logo svg {
    filter: drop-shadow(var(--shadow-sm));
}

.header h1 {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.025em;
}

.subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    font-weight: 400;
}

/* Upload Section */
.upload-area {
    background: var(--surface);
    border: 2px dashed var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-2xl);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    box-shadow: var(--shadow-xs);
}

.upload-area:hover {
    border-color: var(--primary);
    background: var(--surface-hover);
    box-shadow: var(--shadow-md);
}

.upload-area.drag-over {
    border-color: var(--primary);
    background: #eff6ff;
    box-shadow: var(--shadow-md);
}

.upload-icon {
    color: var(--primary);
    margin-bottom: var(--spacing-lg);
    opacity: 0.9;
}

.upload-area h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.upload-area p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-size: 0.9375rem;
}

.file-limit {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* File List */
.file-list {
    margin-top: var(--spacing-xl);
}

.file-list-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.file-list-header h3 {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
}

.btn-clear {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition);
    font-family: inherit;
    font-size: 0.875rem;
    font-weight: 500;
}

.btn-clear:hover {
    background: #fef2f2;
    border-color: var(--danger-light);
    color: var(--danger);
}

.files-container {
    display: grid;
    gap: var(--spacing-sm);
}

.file-item {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    transition: all var(--transition);
    box-shadow: var(--shadow-xs);
}

.file-item:hover {
    border-color: var(--primary-light);
    box-shadow: var(--shadow-sm);
}

.file-icon {
    width: 40px;
    height: 40px;
    background: var(--primary);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.file-info {
    flex: 1;
    min-width: 0;
}

.file-name {
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 0.125rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.file-size {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.file-remove {
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    flex-shrink: 0;
}

.file-remove:hover {
    background: #fef2f2;
    color: var(--danger);
}

/* Action Buttons */
.action-buttons {
    margin-top: var(--spacing-xl);
    display: flex;
    justify-content: center;
}

.btn-primary {
    background: var(--primary);
    border: none;
    color: white;
    padding: 0.875rem 2rem;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition);
    box-shadow: var(--shadow-sm);
    font-family: inherit;
}

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

.btn-primary:active {
    transform: translateY(1px);
}

/* Conversion Section */
.conversion-header {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.conversion-header h2 {
    font-size: 1.375rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--spacing-sm);
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.progress-bar {
    height: 8px;
    background: var(--background-tertiary);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--primary);
    border-radius: var(--radius-full);
    transition: width 0.3s ease;
}

.conversion-list {
    display: grid;
    gap: var(--spacing-sm);
}

.conversion-item {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    box-shadow: var(--shadow-xs);
}

.conversion-item-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-sm);
}

.conversion-status {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.conversion-status.processing {
    background: #eff6ff;
    border: 2px solid var(--primary);
    animation: spin 1s linear infinite;
}

@keyframes spin {
    from {
        transform: rotate(0deg);
    }

    to {
        transform: rotate(360deg);
    }
}

.conversion-status.complete {
    background: #d1fae5;
    border: 2px solid var(--success);
}

.conversion-name {
    flex: 1;
    font-weight: 500;
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.conversion-pages {
    font-size: 0.875rem;
    color: var(--text-muted);
    flex-shrink: 0;
}

/* Download Section */
.download-section {
    text-align: center;
    padding: var(--spacing-2xl) var(--spacing-lg);
}

.success-icon {
    color: var(--success);
    margin-bottom: var(--spacing-xl);
}

.download-section h2 {
    font-size: 1.875rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.download-info {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    font-size: 1.0625rem;
}

.download-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.stat {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    min-width: 140px;
    box-shadow: var(--shadow-sm);
}

.stat-value {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: var(--spacing-xs);
    line-height: 1;
}

.stat-label {
    display: block;
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.btn-download {
    background: var(--success);
    border: none;
    color: white;
    padding: 0.875rem 2rem;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition);
    box-shadow: var(--shadow-sm);
    font-family: inherit;
    margin-bottom: var(--spacing-md);
}

.btn-download:hover {
    background: var(--success-dark);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    font-family: inherit;
}

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

/* Footer */
.footer {
    text-align: center;
    margin-top: var(--spacing-2xl);
    padding-top: var(--spacing-xl);
    color: var(--text-muted);
    font-size: 0.875rem;
    border-top: 1px solid var(--border-light);
}

/* Responsive Design */
@media (max-width: 768px) {
    .header h1 {
        font-size: 1.875rem;
    }

    .container {
        padding: var(--spacing-xl) var(--spacing-md);
    }

    .download-stats {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .stat {
        min-width: auto;
    }

    .upload-area {
        padding: var(--spacing-xl);
    }
}