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

:root {
    --primary-color: #0052CC;
    --primary-hover: #0747A6;
    --secondary-color: #6B778C;
    --success-color: #00875A;
    --danger-color: #DE350B;
    --background: #FAFBFC;
    --surface: #FFFFFF;
    --border: #DFE1E6;
    --text-primary: #172B4D;
    --text-secondary: #6B778C;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    --radius: 8px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    width: 100%;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    padding: 40px 0 30px;
    text-align: center;
    border-bottom: 1px solid var(--border);
    background: var(--surface);
}

h1 {
    font-size: 32px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.subtitle {
    font-size: 16px;
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.language-selector {
    display: flex;
    gap: 8px;
    justify-content: center;
}

.lang-btn {
    padding: 6px 12px;
    border: 1px solid var(--border);
    background: var(--surface);
    color: var(--text-secondary);
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.2s;
}

.lang-btn:hover {
    background: var(--background);
    color: var(--text-primary);
}

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

/* Main Content */
main {
    flex: 1;
    padding: 40px 0;
}

/* Upload Section */
.upload-section {
    max-width: 600px;
    margin: 0 auto;
}

.upload-section.hidden {
    display: none;
}

.file-upload-area {
    background: var(--surface);
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 60px 40px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
}

.file-upload-area:hover,
.file-upload-area.dragover {
    border-color: var(--primary-color);
    background: #F4F5F7;
}

.upload-icon {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.upload-text {
    font-size: 18px;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.upload-subtext {
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.select-btn {
    padding: 10px 24px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}

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

/* Editor Section */
.editor-section {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.editor-section.hidden {
    display: none;
}

/* Toolbar */
.toolbar {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 16px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-sm);
}

.tool-group {
    display: flex;
    gap: 8px;
}

.tool-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 16px;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 4px;
    color: var(--text-primary);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}

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

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

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

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

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

/* Workspace */
.workspace {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 20px;
    height: 600px;
}

/* Pages Panel */
.pages-panel {
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
}

.panel-header {
    padding: 16px;
    border-bottom: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.panel-header h3 {
    font-size: 16px;
    font-weight: 600;
}

.page-count {
    font-size: 14px;
    color: var(--text-secondary);
}

.pages-container {
    flex: 1;
    overflow-y: auto;
    padding: 16px;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
    gap: 12px;
}

.page-thumb {
    position: relative;
    border: 2px solid var(--border);
    border-radius: 4px;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.2s;
    background: white;
}

.page-thumb:hover {
    border-color: var(--primary-color);
    transform: scale(1.05);
}

.page-thumb.selected {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 82, 204, 0.2);
}

.page-thumb canvas {
    width: 100%;
    height: auto;
    display: block;
}

.page-number {
    position: absolute;
    bottom: 4px;
    right: 4px;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 2px 6px;
    border-radius: 2px;
    font-size: 12px;
}

/* Preview Panel */
.preview-panel {
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
}

.zoom-controls {
    display: flex;
    align-items: center;
    gap: 8px;
}

.zoom-btn {
    width: 28px;
    height: 28px;
    border: 1px solid var(--border);
    background: var(--surface);
    border-radius: 4px;
    cursor: pointer;
    font-size: 18px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

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

#zoomLevel {
    font-size: 14px;
    color: var(--text-secondary);
    min-width: 50px;
    text-align: center;
}

.preview-container {
    flex: 1;
    overflow: auto;
    padding: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: #F4F5F7;
}

#previewCanvas {
    box-shadow: var(--shadow-lg);
    background: white;
    max-width: 100%;
    height: auto;
}

/* Footer */
footer {
    padding: 20px 0;
    border-top: 1px solid var(--border);
    background: var(--surface);
}

.privacy-notice {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    color: var(--text-secondary);
    font-size: 14px;
}

.privacy-notice svg {
    color: var(--success-color);
}

/* Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal.hidden {
    display: none;
}

.modal-content {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 24px;
    max-width: 500px;
    width: 90%;
    box-shadow: var(--shadow-lg);
}

.modal-content h3 {
    margin-bottom: 20px;
    font-size: 20px;
    font-weight: 600;
}

.modal-body {
    margin-bottom: 24px;
}

.modal-body label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 500;
}

.modal-body input[type="text"],
.modal-body input[type="number"] {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 14px;
    margin-bottom: 8px;
}

.modal-body input[type="radio"] {
    margin-right: 8px;
}

.help-text {
    font-size: 12px;
    color: var(--text-secondary);
    margin-top: 4px;
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: 12px;
}

.btn-cancel,
.btn-confirm {
    padding: 8px 16px;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}

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

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

.btn-confirm {
    background: var(--primary-color);
    border: none;
    color: white;
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .workspace {
        grid-template-columns: 1fr;
        height: auto;
    }
    
    .pages-panel {
        height: 200px;
    }
    
    .preview-panel {
        height: 400px;
    }
    
    .toolbar {
        flex-direction: column;
        gap: 12px;
    }
    
    .tool-group {
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 24px;
    }
    
    .subtitle {
        font-size: 14px;
    }
    
    .file-upload-area {
        padding: 40px 20px;
    }
    
    .language-selector {
        flex-wrap: wrap;
    }
}