/* Enhanced PDF Viewer Styles */

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

:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --danger-color: #e74c3c;
    --bg-color: #f5f5f5;
    --text-color: #333;
    --border-color: #ddd;

    /* Mastery colors */
    --mastered-color: #27ae60;
    --proficient-color: #3498db;
    --practicing-color: #f39c12;
    --introduced-color: #e67e22;
    --not-started-color: #95a5a6;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    overflow: hidden;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

body.initial-upload-only {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.18) 0%, rgba(118, 75, 162, 0.18) 100%);
}

body.initial-upload-only .upload-menu {
    top: 92px;
    right: 30px;
    left: 30px;
    bottom: 30px;
    width: auto;
    max-width: none;
    padding: 0 24px;
    background: transparent;
}

body.initial-upload-only #pdfPageWrapper {
    display: none;
}

body.initial-upload-only .upload-menu.open {
    display: flex;
    align-items: center;
    justify-content: center;
    pointer-events: auto;
}

body.initial-upload-only .upload-menu.open .upload-menu-content,
body.initial-upload-only .upload-menu .upload-menu-content {
    transform: none;
    opacity: 1;
    max-height: none;
    width: min(520px, 100%);
    box-shadow: 0 32px 80px rgba(44, 62, 80, 0.28);
}

body.initial-upload-only #closeUploadMenu {
    display: none;
}

body.initial-upload-only .upload-menu-title {
    justify-content: center;
    width: 100%;
}

/* Header */
.app-header {
    background: var(--secondary-color);
    color: white;
    padding: 15px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    z-index: 100;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 20px;
}

.header-left h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

.document-title {
    font-size: 1rem;
    opacity: 0.9;
}

.header-right {
    display: flex;
    gap: 10px;
}

.btn-ghost {
    background: rgba(255, 255, 255, 0.12);
    color: #ffffff;
    border: 1px solid rgba(255, 255, 255, 0.2);
    box-shadow: none;
}

.btn-ghost:hover {
    background: rgba(255, 255, 255, 0.2);
    box-shadow: none;
    transform: translateY(0);
}

.btn-ghost:active {
    transform: translateY(0);
    background: rgba(255, 255, 255, 0.28);
}

.btn-ghost.active {
    background: #ffffff;
    color: var(--secondary-color);
    border-color: #ffffff;
    box-shadow: 0 6px 18px rgba(0, 0, 0, 0.18);
}

.btn-ghost.active:hover {
    background: #ffffff;
    color: var(--secondary-color);
}

.btn-ghost:focus-visible,
.btn-icon:focus-visible {
    outline: 3px solid rgba(102, 126, 234, 0.45);
    outline-offset: 2px;
    transform: translateY(0);
}

/* Main Container */
.main-container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* Sidebars */
.sidebar {
    width: 350px;
    background: white;
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: transform 0.3s ease;
}

.sidebar.hidden {
    transform: translateX(-100%);
}

.sidebar-right {
    border-right: none;
    border-left: 1px solid var(--border-color);
}

.sidebar-right.hidden {
    transform: translateX(100%);
}

.sidebar-header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.sidebar-header h3 {
    font-size: 1.2rem;
    color: var(--secondary-color);
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
}

/* PDF Container */
.pdf-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-color);
}

.pdf-container.inactive {
    pointer-events: none;
    opacity: 0.35;
}

.pdf-controls {
    background: white;
    padding: 15px 20px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.checkpoint-summary {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    border-radius: 999px;
    background: rgba(52, 152, 219, 0.12);
    color: var(--secondary-color);
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
}

.checkpoint-summary[data-state="loading"] {
    background: rgba(52, 152, 219, 0.18);
    color: var(--secondary-color);
}

.checkpoint-summary[data-state="error"] {
    background: rgba(231, 76, 60, 0.12);
    color: var(--error-color);
}

.checkpoint-summary.has-progress {
    background: rgba(39, 174, 96, 0.15);
    color: var(--success-color);
}

.checkpoint-summary-content {
    display: flex;
    align-items: center;
    gap: 6px;
}

.checkpoint-summary[data-state="loading"] .checkpoint-summary-content,
.checkpoint-summary[data-state="error"] .checkpoint-summary-content {
    display: none;
}

.checkpoint-summary .summary-count {
    font-weight: 600;
}

.checkpoint-summary-status {
    display: none;
    align-items: center;
    gap: 6px;
}

.checkpoint-summary[data-state="loading"] .checkpoint-summary-status,
.checkpoint-summary[data-state="error"] .checkpoint-summary-status {
    display: flex;
}

.checkpoint-summary-spinner {
    width: 14px;
    height: 14px;
    border: 2px solid rgba(52, 152, 219, 0.35);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.9s linear infinite;
}

.checkpoint-summary[data-state="error"] .checkpoint-summary-spinner {
    display: none;
}

.checkpoint-summary-message {
    font-weight: 600;
}

.checkpoint-summary[data-state="error"] .checkpoint-summary-message {
    color: var(--error-color);
}

.checkpoint-menu {
    position: fixed;
    top: 88px;
    right: 32px;
    width: 320px;
    max-height: calc(100vh - 120px);
    background: #ffffff;
    border-radius: 14px;
    box-shadow: 0 15px 45px rgba(15, 23, 42, 0.25);
    border: 1px solid rgba(99, 102, 241, 0.15);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    z-index: 250;
    animation: fadeInUp 0.18s ease-out;
}

.checkpoint-menu.hidden {
    display: none !important;
}

.checkpoint-menu-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 18px;
    background: linear-gradient(135deg, rgba(99,102,241,0.08), rgba(129,140,248,0.08));
    border-bottom: 1px solid rgba(99, 102, 241, 0.1);
}

.checkpoint-menu-header h3 {
    margin: 0;
    font-size: 1rem;
    font-weight: 600;
    color: #1f2937;
    display: flex;
    align-items: center;
    gap: 8px;
}

.checkpoint-menu-body {
    padding: 12px 0 6px;
    overflow-y: auto;
}

.checkpoint-menu-section {
    padding: 0 18px 18px;
}

.checkpoint-menu-section + .checkpoint-menu-section {
    border-top: 1px solid rgba(15, 23, 42, 0.06);
    padding-top: 18px;
}

.checkpoint-menu-section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 8px;
    color: #4b5563;
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

.checkpoint-menu-section-title {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-weight: 600;
}

.checkpoint-menu-count {
    font-weight: 700;
    color: #1f2937;
}

.checkpoint-menu-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.checkpoint-menu-placeholder {
    padding: 12px 14px;
    border-radius: 10px;
    background: rgba(148, 163, 184, 0.12);
    color: #6b7280;
    font-size: 0.82rem;
    border: 1px dashed rgba(148, 163, 184, 0.35);
}

.checkpoint-menu-item {
    display: flex;
    width: 100%;
    align-items: center;
    justify-content: space-between;
    padding: 12px 14px;
    border-radius: 10px;
    border: 1px solid rgba(148, 163, 184, 0.35);
    background: #ffffff;
    box-shadow: 0 3px 8px rgba(15, 23, 42, 0.08);
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}

.checkpoint-menu-item:hover,
.checkpoint-menu-item:focus {
    transform: translateY(-2px);
    box-shadow: 0 8px 18px rgba(79, 70, 229, 0.18);
    border-color: rgba(99, 102, 241, 0.45);
    outline: none;
}

.checkpoint-menu-item .checkpoint-menu-label {
    display: flex;
    flex-direction: column;
    text-align: left;
    gap: 4px;
}

.checkpoint-menu-item .checkpoint-menu-label strong {
    font-weight: 600;
    color: #111827;
    font-size: 0.95rem;
}

.checkpoint-menu-item .checkpoint-menu-label span {
    font-size: 0.78rem;
    color: #6b7280;
}

.checkpoint-menu-item .checkpoint-menu-status {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-weight: 600;
    font-size: 0.82rem;
}

.checkpoint-menu-item.completed .checkpoint-menu-status {
    color: var(--success-color);
}

.checkpoint-menu-item.pending .checkpoint-menu-status {
    color: var(--warning-color, #f59e0b);
}

.checkpoint-menu-empty {
    padding: 32px 24px 28px;
    text-align: center;
    color: #6b7280;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.checkpoint-menu-empty i {
    font-size: 1.6rem;
    color: rgba(99, 102, 241, 0.7);
}

.checkpoint-menu-empty p {
    margin: 0;
    font-size: 0.9rem;
}

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

.page-info {
    font-size: 0.9rem;
    color: var(--text-color);
    min-width: 120px;
    text-align: center;
}

#zoomLevel {
    min-width: 50px;
    text-align: center;
    font-size: 0.9rem;
}

/* PDF Canvas Container */
.pdf-canvas-container {
    flex: 1;
    overflow: auto;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 20px;
}

.pdf-empty-state {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    color: #7f8c8d;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    pointer-events: none;
    z-index: 5;
    max-width: 320px;
}

.pdf-empty-state i {
    font-size: 42px;
    color: rgba(127, 140, 141, 0.65);
}

.pdf-empty-state p {
    font-size: 1rem;
    line-height: 1.5;
}

/* PDF Page Wrapper - contains canvas and text layer */
.pdf-page-wrapper {
    position: relative;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    background: white;
}

#pdfCanvas {
    display: block;
}

/* PDF.js Text Layer */
.textLayer {
    position: absolute;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    overflow: hidden;
    opacity: 1;
    line-height: 1.0;
    pointer-events: none;
}

.textLayer span {
    color: transparent;
    position: absolute;
    white-space: pre;
    cursor: text;
    transform-origin: 0% 0%;
    pointer-events: auto;
}

/* Checkpoint text - no visual styling (only question mark icon shown) */
.textLayer span.checkpoint-text {
    cursor: pointer;
    transition: all 0.2s ease;
}

.textLayer span.checkpoint-text:hover {
    /* No visual change on hover */
}

.textLayer span.checkpoint-text.completed {
    /* No visual change when completed */
}

/* Checkpoint Overlay */
.checkpoint-overlay,
.highlight-overlay {
    position: absolute;
    top: 0;
    left: 0;
    pointer-events: none;
    z-index: 10;
}

.checkpoint-marker {
    position: absolute;
    cursor: pointer;
    pointer-events: all;
    transition: all 0.2s ease;
}

/* Removed: checkpoint underlines - now using icon-only approach */

/* Checkpoint icon - positioned right after text */
.checkpoint-icon {
    position: absolute !important;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-color);
    color: white !important;
    border-radius: 50%;
    font-weight: bold;
    box-shadow: 0 2px 5px rgba(0,0,0,0.25);
    cursor: pointer;
    transition: all 0.15s ease;
    pointer-events: all;
    z-index: 100;
    line-height: 1;
    border: none;
    padding: 0;
    transform-origin: 100% 50%;
}

.checkpoint-icon:hover {
    transform: translateY(-50%) scale(1.2) !important;
    box-shadow: 0 3px 8px rgba(0,0,0,0.35);
    background: #2980b9;
}

.checkpoint-icon.completed {
    background: var(--success-color);
}

.checkpoint-icon.completed:hover {
    background: #229954;
}

.checkpoint-icon:focus-visible {
    outline: 3px solid rgba(99, 102, 241, 0.45);
    outline-offset: 2px;
}

/* Concept highlights */
.concept-highlight {
    background: rgba(241, 196, 15, 0.3);
    border-bottom: 1px solid rgba(241, 196, 15, 0.6);
    cursor: help;
}

.concept-highlight:hover {
    background: rgba(241, 196, 15, 0.4);
}

/* Question Popover */
.question-popover {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: white;
    border-radius: 8px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
    min-width: 500px;
    max-width: 700px;
    max-height: 80vh;
    overflow: hidden;
    z-index: 1000;
    display: flex;
    flex-direction: column;
}

.question-popover.hidden {
    display: none;
}

.popover-header {
    background: var(--secondary-color);
    color: white;
    padding: 15px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.popover-header h4 {
    font-size: 1.1rem;
}

.popover-body {
    padding: 25px;
    overflow-y: auto;
    flex: 1;
}

.question-content {
    margin-bottom: 20px;
}

.question-prompt {
    font-size: 1.1rem;
    font-weight: 500;
    margin-bottom: 20px;
    color: var(--secondary-color);
}

.question-options {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.option-item {
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 10px;
}

.option-item:hover {
    border-color: var(--primary-color);
    background: rgba(52, 152, 219, 0.05);
}

.option-item.selected {
    border-color: var(--primary-color);
    background: rgba(52, 152, 219, 0.1);
}

.option-item input[type="radio"] {
    cursor: pointer;
}

.short-answer-input {
    width: 100%;
    min-height: 100px;
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 6px;
    font-family: inherit;
    font-size: 1rem;
    resize: vertical;
}

.short-answer-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.question-actions {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    gap: 12px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

.question-actions .question-loading {
    display: none;
    align-items: center;
    gap: 8px;
    font-size: 0.95rem;
    color: var(--secondary-color);
}

.question-actions.loading .question-loading {
    display: flex;
}

.question-actions.loading button {
    opacity: 0.6;
    pointer-events: none;
    cursor: not-allowed;
}

.spinner.spinner-sm {
    width: 22px;
    height: 22px;
    border-width: 3px;
}

/* Feedback Modal */
.feedback-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: 2000;
}

.feedback-modal.hidden {
    display: none;
}

.modal-content {
    background: white;
    border-radius: 8px;
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.feedback-header {
    padding: 20px;
    font-size: 1.3rem;
    font-weight: 600;
    text-align: center;
}

.feedback-header.correct {
    background: var(--success-color);
    color: white;
}

.feedback-header.incorrect {
    background: var(--danger-color);
    color: white;
}

.feedback-body {
    padding: 25px;
    overflow-y: auto;
    flex: 1;
}

.feedback-explanation {
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 15px;
}

.feedback-correct-answer {
    background: rgba(39, 174, 96, 0.1);
    padding: 15px;
    border-radius: 6px;
    border-left: 4px solid var(--success-color);
    margin-top: 15px;
}

.feedback-actions {
    padding: 20px;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: center;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

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

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

.btn-primary:hover {
    background: #2980b9;
}

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

.btn-secondary:hover {
    background: #34495e;
}

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

.btn-icon {
    width: 40px;
    height: 40px;
    padding: 0;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
}

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

/* Progress Stats */
.progress-stats {
    display: grid;
    grid-template-columns: 1fr;
    gap: 15px;
    margin-bottom: 25px;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 20px;
    border-radius: 8px;
    text-align: center;
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 5px;
}

.stat-label {
    font-size: 0.85rem;
    opacity: 0.9;
}

/* Concept List */
.concept-list {
    margin-bottom: 25px;
}

.concept-list h4 {
    margin-bottom: 15px;
    color: var(--secondary-color);
}

.concept-item {
    padding: 12px;
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-bottom: 10px;
}

.concept-name {
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--secondary-color);
}

.concept-progress {
    display: flex;
    align-items: center;
    gap: 10px;
}

.progress-bar {
    flex: 1;
    height: 8px;
    background: var(--border-color);
    border-radius: 4px;
    overflow: hidden;
}

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

.progress-fill.mastered {
    background: var(--mastered-color);
}

.progress-fill.proficient {
    background: var(--proficient-color);
}

.progress-fill.practicing {
    background: var(--practicing-color);
}

.progress-percent {
    font-size: 0.85rem;
    font-weight: 600;
    min-width: 40px;
}

/* Concept Map */
#conceptMapContainer {
    min-height: 400px;
    background: white;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-bottom: 20px;
}

.concept-legend {
    background: var(--bg-color);
    padding: 15px;
    border-radius: 6px;
}

.concept-legend h4 {
    margin-bottom: 12px;
    font-size: 0.95rem;
    color: var(--secondary-color);
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 8px;
    font-size: 0.85rem;
}

.legend-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.legend-dot.mastered {
    background: var(--mastered-color);
}

.legend-dot.proficient {
    background: var(--proficient-color);
}

.legend-dot.practicing {
    background: var(--practicing-color);
}

.legend-dot.introduced {
    background: var(--introduced-color);
}

.legend-dot.not-started {
    background: var(--not-started-color);
}

/* Loading Indicator */
.loading-indicator {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255,255,255,0.95);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    z-index: 3000;
}

.loading-indicator.hidden {
    display: none;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.loading-indicator p {
    margin-top: 15px;
    color: var(--secondary-color);
    font-size: 1.1rem;
}

.upload-menu {
    position: fixed;
    top: 92px;
    right: 30px;
    width: 420px;
    max-width: calc(100% - 60px);
    z-index: 160;
    pointer-events: none;
    display: none;
}

.upload-menu-content {
    background: #ffffff;
    border-radius: 14px;
    box-shadow: 0 22px 48px rgba(44, 62, 80, 0.28);
    overflow: hidden;
    transform: translateY(-14px);
    opacity: 0;
    transition: transform 0.25s ease, opacity 0.25s ease;
    max-height: calc(100vh - 140px);
    display: flex;
    flex-direction: column;
}

.upload-menu.open .upload-menu-content {
    transform: translateY(0);
    opacity: 1;
}

.upload-menu.open {
    pointer-events: auto;
    display: block;
}

.upload-menu-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 18px 22px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.12) 0%, rgba(118, 75, 162, 0.08) 100%);
}

.upload-menu-title {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--secondary-color);
}

.upload-menu-title i {
    color: var(--primary-color);
    font-size: 1.1rem;
}

.upload-menu.is-uploading .upload-menu-title i {
    animation: uploadPulse 1.6s ease-in-out infinite;
}

@keyframes uploadPulse {
    0% {
        transform: scale(1);
        opacity: 0.65;
    }
    50% {
        transform: scale(1.12);
        opacity: 1;
    }
    100% {
        transform: scale(1);
        opacity: 0.65;
    }
}

.upload-menu-body {
    padding: 26px 28px 30px 28px;
    background: #ffffff;
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 24px;
    overflow-y: auto;
}

.upload-drop-zone {
    padding: 40px 30px;
    background: white;
    border: 2px dashed #d1d5db;
    border-radius: 8px;
    transition: all 0.3s ease;
    position: relative;
    cursor: pointer;
}

.upload-drop-zone:hover {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.02);
}

.upload-drop-zone.dragover {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.05);
}

.upload-icon {
    margin-bottom: 20px;
}

.upload-icon i {
    font-size: 48px;
    color: #333333;
    transition: all 0.3s ease;
}

.upload-drop-zone:hover .upload-icon i {
    color: #667eea;
}

.upload-drop-zone h3 {
    color: #333333;
    font-size: 1.2rem;
    font-weight: 600;
    margin: 0 0 12px 0;
    line-height: 1.4;
}

.file-formats {
    color: #888888;
    font-size: 0.9rem;
    margin: 0 0 25px 0;
    font-weight: 400;
}

.btn-browse {
    background: white;
    color: #333333;
    border: 1px solid #cccccc;
    padding: 12px 24px;
    border-radius: 6px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-block;
}

.btn-browse:hover {
    border-color: #667eea;
    color: #667eea;
    background: rgba(102, 126, 234, 0.05);
}

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

.btn-large {
    padding: 20px 50px;
    font-size: 1.15rem;
    font-weight: 600;
    width: 100%;
    max-width: 450px;
    border-radius: 12px;
    box-shadow: 0 4px 14px rgba(102, 126, 234, 0.3);
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-large:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

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

.btn-large:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.upload-progress {
    margin-top: 0;
    text-align: left;
}

.upload-menu-footer {
    margin-top: 18px;
    font-size: 0.85rem;
    color: #95a5a6;
    text-align: center;
}

.progress-bar-wrapper {
    width: 100%;
    height: 8px;
    background: #ecf0f1;
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 15px;
}

.progress-bar-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
    transition: width 0.3s ease;
    animation: pulse 1.5s ease-in-out infinite;
}

.progress-message {
    color: #7f8c8d;
    font-size: 1rem;
    margin: 0;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Responsive */
@media (max-width: 1024px) {
    .sidebar {
        position: absolute;
        z-index: 50;
        height: 100%;
    }
}

@media (max-width: 900px) {
    .upload-menu {
        top: 88px;
        right: 20px;
        max-width: calc(100% - 40px);
    }

    .upload-menu-body {
        padding: 22px 22px 26px 22px;
    }
}

@media (max-width: 640px) {
    .header-left h1 {
        font-size: 1.25rem;
    }

    .upload-menu {
        top: 82px;
        right: 16px;
        left: 16px;
        width: auto;
        max-width: none;
    }

    .upload-menu-content {
        border-radius: 12px;
        max-height: calc(100vh - 120px);
    }

    .upload-drop-zone {
        padding: 32px 22px;
    }
}