/* Global Styles */
:root {
    --primary-color: #2C5AA0;
    --secondary-color: #FF6B6B;
    --success-color: #4CAF50;
    --warning-color: #FFA726;
    --danger-color: #EF5350;
    --dark: #2C3E50;
    --light: #ECF0F1;
    --white: #FFFFFF;
    --gray-100: #F8F9FA;
    --gray-200: #E9ECEF;
    --gray-300: #DEE2E6;
    --gray-400: #CED4DA;
    --gray-600: #6C757D;
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-success: linear-gradient(135deg, #4CAF50 0%, #8BC34A 100%);
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 8px rgba(0,0,0,0.15);
    --shadow-lg: 0 10px 30px rgba(0,0,0,0.2);
    --border-radius: 12px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--dark);
    background: var(--gradient-primary);
    min-height: 100vh;
}

/* Progress Bar */
.top-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: rgba(255,255,255,0.2);
    z-index: 9999;
}

.progress-fill {
    height: 100%;
    background: var(--gradient-success);
    width: 0%;
    transition: width 0.5s ease;
    box-shadow: 0 0 10px rgba(76, 175, 80, 0.5);
}

/* Header */
.main-header {
    background: rgba(255,255,255,0.98);
    padding: 20px 30px;
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
    animation: slideDown 0.5s ease;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
}

.main-header h1 {
    font-size: 2em;
    color: var(--primary-color);
    margin-bottom: 5px;
}

.main-header h1 i {
    margin-right: 10px;
    color: var(--secondary-color);
}

.subtitle {
    color: var(--gray-600);
    font-size: 1.1em;
}

.progress-stats {
    margin-top: 10px;
    font-size: 0.95em;
    color: var(--gray-600);
}

.separator {
    margin: 0 10px;
    color: var(--gray-400);
}

/* Main Container */
.main-container {
    display: flex;
    max-width: 1400px;
    margin: 20px auto;
    gap: 20px;
    padding: 0 20px;
}

/* Sidebar */
.sidebar {
    width: 300px;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    padding: 20px;
    height: fit-content;
    position: sticky;
    top: 100px;
    animation: slideInLeft 0.6s ease;
}

@keyframes slideInLeft {
    from {
        transform: translateX(-50px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--gray-200);
}

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

.close-sidebar {
    display: none;
    background: none;
    border: none;
    font-size: 1.5em;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
}

.close-sidebar:hover {
    color: var(--danger-color);
}

/* Lesson Navigation */
.lesson-nav {
    display: flex;
    flex-direction: column;
    gap: 8px;
    max-height: 500px;
    overflow-y: auto;
    padding-right: 10px;
}

.lesson-nav::-webkit-scrollbar {
    width: 6px;
}

.lesson-nav::-webkit-scrollbar-track {
    background: var(--gray-100);
    border-radius: 10px;
}

.lesson-nav::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 10px;
}

.lesson-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
}

.lesson-item:hover {
    background: var(--gray-100);
    transform: translateX(5px);
}

.lesson-item.active {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    border-color: var(--primary-color);
}

.lesson-item.completed {
    opacity: 0.7;
}

.lesson-number {
    background: var(--gradient-primary);
    color: white;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    flex-shrink: 0;
}

.lesson-item.completed .lesson-number {
    background: var(--success-color);
}

.lesson-title {
    flex: 1;
    font-size: 0.95em;
    color: var(--dark);
}

.lesson-complete {
    color: var(--success-color);
    font-size: 1.2em;
    opacity: 0;
    transition: var(--transition);
}

.lesson-item.completed .lesson-complete {
    opacity: 1;
}

.sidebar-footer {
    margin-top: 20px;
    padding-top: 15px;
    border-top: 2px solid var(--gray-200);
}

/* Content Area */
.content-area {
    flex: 1;
    animation: fadeInUp 0.6s ease;
}

@keyframes fadeInUp {
    from {
        transform: translateY(30px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.lesson-container {
    background: white;
    border-radius: var(--border-radius);
    padding: 40px;
    box-shadow: var(--shadow-lg);
    margin-bottom: 20px;
    min-height: 400px;
}

/* Buttons */
.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1em;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
    text-decoration: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-sm);
}

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

.btn-secondary {
    background: var(--gray-200);
    color: var(--dark);
}

.btn-secondary:hover {
    background: var(--gray-300);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--gray-300);
    color: var(--dark);
}

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

.btn-small {
    padding: 8px 16px;
    font-size: 0.9em;
}

.btn-large {
    padding: 16px 32px;
    font-size: 1.1em;
}

/* Simulator Container */
.simulator-container {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    margin-bottom: 20px;
    animation: scaleIn 0.4s ease;
}

@keyframes scaleIn {
    from {
        transform: scale(0.95);
        opacity: 0;
    }
    to {
        transform: scale(1);
        opacity: 1;
    }
}

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

.simulator-title {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 600;
    font-size: 1.1em;
}

.close-simulator {
    background: rgba(255,255,255,0.2);
    border: none;
    color: white;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 6px;
}

.close-simulator:hover {
    background: rgba(255,255,255,0.3);
}

/* Zotero Interface Simulation */
.zotero-interface {
    background: #F5F5F5;
}

.zotero-toolbar {
    background: #E8E8E8;
    padding: 10px;
    display: flex;
    align-items: center;
    gap: 8px;
    border-bottom: 1px solid #D0D0D0;
}

.toolbar-btn {
    background: white;
    border: 1px solid #CCC;
    padding: 8px 12px;
    border-radius: 4px;
    cursor: pointer;
    transition: var(--transition);
    color: var(--dark);
}

.toolbar-btn:hover {
    background: var(--gray-100);
    border-color: var(--primary-color);
}

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

.toolbar-divider {
    width: 1px;
    height: 24px;
    background: #CCC;
    margin: 0 8px;
}

.toolbar-search {
    flex: 1;
    position: relative;
    max-width: 400px;
}

.toolbar-search input {
    width: 100%;
    padding: 8px 35px 8px 12px;
    border: 1px solid #CCC;
    border-radius: 4px;
    font-size: 0.95em;
}

.toolbar-search i {
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--gray-600);
}

/* Zotero Main Panels */
.zotero-main {
    display: flex;
    height: 500px;
    border-bottom: 1px solid #D0D0D0;
}

.zotero-panel {
    background: white;
    border-right: 1px solid #D0D0D0;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.zotero-panel:last-child {
    border-right: none;
}

.left-panel {
    width: 250px;
}

.middle-panel {
    flex: 1;
}

.right-panel {
    width: 300px;
}

.panel-header {
    padding: 12px;
    background: #F8F8F8;
    border-bottom: 1px solid #E0E0E0;
    font-weight: 600;
    color: var(--dark);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Collections Tree */
.collections-tree {
    flex: 1;
    overflow-y: auto;
    padding: 8px;
}

.collection-item {
    padding: 8px 12px;
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    border-radius: 4px;
    transition: var(--transition);
    color: var(--dark);
}

.collection-item:hover {
    background: var(--gray-100);
}

.collection-item.active {
    background: var(--primary-color);
    color: white;
}

.collection-item i {
    font-size: 0.9em;
}

.collection-item .item-count {
    margin-left: auto;
    background: var(--gray-200);
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.85em;
}

.collection-item.active .item-count {
    background: rgba(255,255,255,0.3);
}

.collections-section {
    margin-top: 15px;
}

.section-header {
    padding: 8px 12px;
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    font-weight: 600;
    color: var(--gray-600);
    transition: var(--transition);
}

.section-header:hover {
    color: var(--primary-color);
}

.section-header i {
    font-size: 0.8em;
    transition: var(--transition);
}

.section-header.expanded i {
    transform: rotate(90deg);
}

.collections-list {
    padding-left: 20px;
}

/* Items Table */
.items-table {
    flex: 1;
    overflow: auto;
    display: flex;
    flex-direction: column;
}

.table-header {
    display: grid;
    grid-template-columns: 2fr 1.5fr 0.5fr;
    gap: 10px;
    padding: 12px;
    background: #F8F8F8;
    border-bottom: 1px solid #E0E0E0;
    font-weight: 600;
    font-size: 0.9em;
    color: var(--gray-600);
}

.items-list {
    flex: 1;
    overflow-y: auto;
}

.item-row {
    display: grid;
    grid-template-columns: 2fr 1.5fr 0.5fr;
    gap: 10px;
    padding: 12px;
    border-bottom: 1px solid #F0F0F0;
    cursor: pointer;
    transition: var(--transition);
}

.item-row:hover {
    background: var(--gray-100);
}

.item-row.selected {
    background: #E3F2FD;
    border-left: 3px solid var(--primary-color);
}

.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    color: var(--gray-600);
    text-align: center;
    padding: 40px 20px;
}

.empty-state i {
    font-size: 4em;
    margin-bottom: 15px;
    color: var(--gray-400);
}

.empty-state .hint {
    font-size: 0.9em;
    color: var(--gray-500);
    margin-top: 8px;
}

/* Right Panel Tabs */
.panel-tabs {
    display: flex;
    background: #F8F8F8;
    border-bottom: 1px solid #E0E0E0;
}

.tab-btn {
    flex: 1;
    padding: 10px;
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: 0.9em;
    color: var(--gray-600);
    border-bottom: 3px solid transparent;
    transition: var(--transition);
}

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

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

.panel-content {
    flex: 1;
    overflow-y: auto;
}

.tab-content {
    display: none;
    padding: 15px;
    height: 100%;
}

.tab-content.active {
    display: block;
}

/* Task Guide */
.task-guide {
    position: absolute;
    bottom: 20px;
    right: 20px;
    width: 350px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.2);
    z-index: 1000;
    animation: slideInRight 0.4s ease;
}

@keyframes slideInRight {
    from {
        transform: translateX(100px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.guide-content {
    padding: 20px;
}

.guide-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.guide-header h3 {
    color: var(--primary-color);
    font-size: 1.1em;
    display: flex;
    align-items: center;
    gap: 8px;
}

.task-step {
    background: var(--gray-200);
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.85em;
    color: var(--gray-600);
}

.guide-body {
    margin-bottom: 15px;
}

.task-instruction {
    font-size: 1.05em;
    color: var(--dark);
    margin-bottom: 10px;
    line-height: 1.5;
}

.task-hint {
    background: #FFF9E6;
    border-left: 3px solid var(--warning-color);
    padding: 12px;
    border-radius: 6px;
    font-size: 0.95em;
    display: flex;
    align-items: start;
    gap: 10px;
}

.task-hint i {
    color: var(--warning-color);
    margin-top: 2px;
}

.guide-footer {
    display: flex;
    gap: 10px;
}

.guide-footer .btn {
    flex: 1;
    justify-content: center;
}

/* Navigation */
.lesson-navigation {
    display: flex;
    justify-content: space-between;
    gap: 15px;
    margin-top: 20px;
}

/* Floating Action Buttons */
.fab-container {
    position: fixed;
    bottom: 30px;
    right: 30px;
    display: flex;
    flex-direction: column;
    gap: 15px;
    z-index: 1000;
}

.fab {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--gradient-primary);
    color: white;
    border: none;
    box-shadow: var(--shadow-lg);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3em;
    transition: var(--transition);
}

.fab:hover {
    transform: scale(1.1);
    box-shadow: 0 12px 40px rgba(102, 126, 234, 0.4);
}

/* Modals */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.7);
    z-index: 10000;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.3s ease;
}

.modal.show {
    display: flex;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.modal-content {
    background: white;
    border-radius: var(--border-radius);
    padding: 40px;
    max-width: 500px;
    width: 90%;
    position: relative;
    animation: scaleIn 0.3s ease;
}

.close-modal {
    position: absolute;
    top: 15px;
    right: 15px;
    background: none;
    border: none;
    font-size: 1.5em;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
}

.close-modal:hover {
    color: var(--danger-color);
}

/* Completion Modal */
.completion-animation {
    text-align: center;
    margin-bottom: 20px;
}

.completion-animation i {
    font-size: 5em;
    color: #FFD700;
    animation: bounce 1s ease infinite;
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

.completion-content h2 {
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.completion-content p {
    text-align: center;
    color: var(--gray-600);
    margin-bottom: 25px;
}

.completion-stats {
    display: flex;
    gap: 20px;
    justify-content: center;
    margin: 30px 0;
}

.stat {
    text-align: center;
}

.stat i {
    font-size: 2em;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.stat span {
    display: block;
    font-size: 1.5em;
    font-weight: bold;
    color: var(--dark);
    margin-bottom: 5px;
}

.stat p {
    font-size: 0.9em;
    color: var(--gray-600);
    margin: 0;
}

/* Certificate */
.certificate {
    border: 10px double var(--primary-color);
    padding: 40px;
    margin: 20px 0;
}

.certificate-border {
    border: 2px solid var(--gray-300);
    padding: 30px;
}

.certificate-header {
    text-align: center;
    margin-bottom: 30px;
}

.certificate-header i {
    font-size: 4em;
    color: #FFD700;
}

.certificate-header h1 {
    color: var(--primary-color);
    margin-top: 15px;
}

.certificate-body {
    text-align: center;
    margin: 30px 0;
}

.certificate-text {
    font-size: 1.1em;
    color: var(--gray-600);
    margin: 10px 0;
}

.certificate-name {
    font-size: 2.5em;
    color: var(--primary-color);
    margin: 20px 0;
    font-style: italic;
}

.certificate-body h3 {
    font-size: 1.8em;
    color: var(--dark);
    margin: 20px 0;
}

.certificate-date {
    font-size: 1em;
    color: var(--gray-600);
    margin-top: 20px;
}

.certificate-footer {
    display: flex;
    justify-content: center;
    margin-top: 40px;
}

.signature {
    text-align: center;
    border-top: 2px solid var(--dark);
    padding-top: 10px;
    min-width: 200px;
}

.signature p {
    margin: 5px 0;
    color: var(--dark);
}

.signature-title {
    font-size: 0.9em;
    color: var(--gray-600);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .main-container {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        position: relative;
        top: 0;
    }
    
    .zotero-main {
        height: auto;
        flex-direction: column;
    }
    
    .left-panel,
    .middle-panel,
    .right-panel {
        width: 100%;
        min-height: 300px;
        border-right: none;
        border-bottom: 1px solid #D0D0D0;
    }
    
    .task-guide {
        position: relative;
        width: 100%;
        bottom: 0;
        right: 0;
        margin-top: 20px;
    }
}

@media (max-width: 768px) {
    .main-header h1 {
        font-size: 1.5em;
    }
    
    .subtitle {
        font-size: 1em;
    }
    
    .progress-stats {
        font-size: 0.85em;
    }
    
    .lesson-container {
        padding: 20px;
    }
    
    .sidebar {
        position: fixed;
        left: -100%;
        top: 0;
        bottom: 0;
        width: 280px;
        z-index: 1001;
        transition: left 0.3s ease;
        border-radius: 0;
    }
    
    .sidebar.show {
        left: 0;
    }
    
    .close-sidebar {
        display: block;
    }
    
    .lesson-navigation {
        flex-direction: column;
    }
    
    .modal-content {
        padding: 25px;
    }
}