:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --secondary: #8b5cf6;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --dark: #1f2937;
    --dark-light: #374151;
    --gray: #6b7280;
    --gray-light: #9ca3af;
    --bg: #f9fafb;
    --bg-secondary: #f3f4f6;
    --border: #e5e7eb;
    --white: #ffffff;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg);
    color: var(--dark);
    overflow: hidden;
}

/* Header */
.header {
    background: var(--white);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow);
    position: relative;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 100%;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark);
}

.logo i {
    color: var(--primary);
    font-size: 1.75rem;
}

.logo .pro {
    color: var(--primary);
    font-size: 1.25rem;
}

.header-actions {
    display: flex;
    gap: 0.75rem;
}

.btn-header {
    padding: 0.625rem 1.25rem;
    border: 1px solid var(--border);
    background: var(--white);
    color: var(--dark);
    border-radius: 0.5rem;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s;
}

.btn-header:hover {
    background: var(--bg);
    border-color: var(--gray-light);
}

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

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

/* Main Container */
.main-container {
    display: grid;
    grid-template-columns: 80px 1fr 320px;
    height: calc(100vh - 65px);
    overflow: hidden;
}

/* Sidebar Left */
.sidebar-left {
    background: var(--white);
    border-right: 1px solid var(--border);
    overflow-y: auto;
    padding: 1rem 0.5rem;
}

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

.tool-group-title {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--gray);
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0 0.25rem;
}

.tool-group-title i {
    font-size: 0.875rem;
}

.tool-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
}

.tool-btn {
    width: 100%;
    aspect-ratio: 1;
    border: 2px solid var(--border);
    background: var(--white);
    border-radius: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: var(--gray);
    transition: all 0.2s;
}

.tool-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: #eef2ff;
}

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

/* Workspace */
.workspace {
    background: var(--bg-secondary);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.toolbar {
    background: var(--white);
    border-bottom: 1px solid var(--border);
    padding: 0.75rem 1.5rem;
    display: flex;
    gap: 2rem;
    align-items: center;
}

.toolbar-group {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.toolbar-btn {
    width: 36px;
    height: 36px;
    border: 1px solid var(--border);
    background: var(--white);
    border-radius: 0.375rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--gray);
    transition: all 0.2s;
}

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

.zoom-level {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--dark);
    min-width: 50px;
    text-align: center;
}

.page-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--dark);
}

#current-page-input {
    width: 50px;
    padding: 0.375rem;
    border: 1px solid var(--border);
    border-radius: 0.375rem;
    text-align: center;
    font-size: 0.875rem;
}

/* Canvas Container */
.canvas-container {
    flex: 1;
    overflow: auto;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

.upload-zone {
    background: var(--white);
    border: 3px dashed var(--border);
    border-radius: 1rem;
    padding: 4rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    max-width: 600px;
    width: 100%;
}

.upload-zone:hover {
    border-color: var(--primary);
    background: #f8f9ff;
}

.upload-content i {
    font-size: 4rem;
    color: var(--primary);
    margin-bottom: 1.5rem;
}

.upload-content h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--dark);
}

.upload-content p {
    color: var(--gray);
    margin-bottom: 1.5rem;
}

.btn-upload {
    padding: 0.875rem 2rem;
    background: var(--primary);
    color: var(--white);
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.2s;
}

.btn-upload:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.upload-hint {
    margin-top: 1rem;
    font-size: 0.875rem;
    color: var(--gray-light);
}

/* PDF Viewer */
.pdf-viewer {
    position: relative;
    box-shadow: var(--shadow-lg);
    background: var(--white);
}

#pdf-canvas {
    display: block;
    max-width: 100%;
}

#annotation-canvas {
    position: absolute;
    top: 0;
    left: 0;
    cursor: crosshair;
}

/* Sidebar Right */
.sidebar-right {
    background: var(--white);
    border-left: 1px solid var(--border);
    overflow-y: auto;
    display: flex;
    flex-direction: column;
}

.properties-panel {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border);
}

.panel-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.property-section {
    margin-bottom: 1.5rem;
}

.property-section h4 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--dark);
    margin-bottom: 1rem;
}

.property-section label {
    display: block;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--gray);
    margin-bottom: 0.5rem;
    margin-top: 1rem;
}

.property-section textarea,
.property-section select,
.property-section input[type="text"],
.property-section input[type="number"] {
    width: 100%;
    padding: 0.625rem;
    border: 1px solid var(--border);
    border-radius: 0.375rem;
    font-size: 0.875rem;
    font-family: inherit;
}

.property-section textarea {
    resize: vertical;
    min-height: 80px;
}

.input-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.input-group input {
    flex: 1;
}

.input-suffix {
    font-size: 0.875rem;
    color: var(--gray);
}

.color-picker {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.color-picker input[type="color"] {
    width: 50px;
    height: 36px;
    border: 1px solid var(--border);
    border-radius: 0.375rem;
    cursor: pointer;
}

.color-picker span {
    font-size: 0.875rem;
    font-family: monospace;
    color: var(--dark);
}

.text-style-buttons {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
}

.style-btn {
    flex: 1;
    padding: 0.625rem;
    border: 1px solid var(--border);
    background: var(--white);
    border-radius: 0.375rem;
    cursor: pointer;
    font-size: 1rem;
    color: var(--gray);
    transition: all 0.2s;
}

.style-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

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

.doc-info {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.info-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.875rem;
}

.info-item i {
    color: var(--primary);
    width: 20px;
}

.preservation-score {
    text-align: center;
}

.score-circle {
    display: flex;
    justify-content: center;
    margin: 1.5rem 0;
}

.score-description {
    font-size: 0.8125rem;
    color: var(--gray);
}

/* Pages Panel */
.pages-panel {
    padding: 1.5rem;
    flex: 1;
}

.pages-list {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.page-thumb {
    border: 2px solid var(--border);
    border-radius: 0.5rem;
    padding: 0.5rem;
    cursor: pointer;
    transition: all 0.2s;
    background: var(--white);
}

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

.page-thumb.active {
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.2);
}

.page-thumb img {
    width: 100%;
    display: block;
    border-radius: 0.25rem;
}

.page-number {
    text-align: center;
    font-size: 0.75rem;
    color: var(--gray);
    margin-top: 0.5rem;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.loading-spinner {
    background: var(--white);
    padding: 3rem;
    border-radius: 1rem;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

.loading-spinner i {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: 1rem;
}

.loading-spinner p {
    font-size: 1.125rem;
    color: var(--dark);
    font-weight: 600;
}

/* Scrollbars */
::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg);
}

::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--gray-light);
}

/* Responsive */
@media (max-width: 1200px) {
    .main-container {
        grid-template-columns: 70px 1fr 280px;
    }
}

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

    .sidebar-left,
    .sidebar-right {
        display: none;
    }
}