/* ================================================================
   LearnHub -- E-Learning LMS Theme
   Modern purple/indigo educational design
   ================================================================ */

/* ---- CSS Variables -------------------------------------------------- */
:root {
    --primary: #6C5CE7;
    --primary-dark: #5A4BD1;
    --primary-light: #A29BFE;
    --primary-bg: #F0EDFF;
    --secondary: #00CEC9;
    --secondary-dark: #00B5B0;
    --accent: #FD79A8;
    --accent-light: #FEE2EC;
    --success: #00B894;
    --success-bg: #E6F9F3;
    --warning: #FDCB6E;
    --warning-bg: #FFF8E6;
    --danger: #E17055;
    --danger-bg: #FDEDEA;
    --info: #74B9FF;
    --info-bg: #E8F4FF;
    --bg: #F7F6FB;
    --bg-card: #FFFFFF;
    --bg-sidebar: #2D1B69;
    --text: #2D3436;
    --text-secondary: #636E72;
    --text-light: #B2BEC3;
    --border: #E8E4F0;
    --border-light: #F0ECF5;
    --shadow-sm: 0 1px 3px rgba(108, 92, 231, 0.08);
    --shadow-md: 0 4px 12px rgba(108, 92, 231, 0.12);
    --shadow-lg: 0 8px 24px rgba(108, 92, 231, 0.16);
    --shadow-xl: 0 16px 48px rgba(108, 92, 231, 0.2);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition: 0.2s ease;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

/* ---- Reset ---------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}
a { text-decoration: none; color: var(--primary); transition: color var(--transition); }
a:hover { color: var(--primary-dark); }
img { max-width: 100%; display: block; }
button { cursor: pointer; font-family: inherit; }
input, select, textarea { font-family: inherit; font-size: 1rem; }

/* ---- Navbar --------------------------------------------------------- */
.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
    height: 64px;
    background: var(--bg-card);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}
.nav-brand .logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--primary);
}
.logo-icon { font-size: 1.6rem; }
.nav-links { display: flex; gap: 0.5rem; }
.nav-link {
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: all var(--transition);
}
.nav-link:hover, .nav-link.active {
    color: var(--primary);
    background: var(--primary-bg);
}
.nav-user {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.user-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.9rem;
}
.user-name { font-weight: 500; color: var(--text); font-size: 0.9rem; }

/* ---- Main Content --------------------------------------------------- */
.main-content {
    flex: 1;
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    padding: 2rem;
}

/* ---- Loading Spinner ------------------------------------------------ */
.loading-spinner {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 4rem 0;
    color: var(--text-secondary);
}
.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-bottom: 1rem;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---- Cards ---------------------------------------------------------- */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition);
    overflow: hidden;
}
.card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}
.card-header {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-light);
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.card-header h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text);
}
.card-body { padding: 1.5rem; }
.card-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-light);
    background: var(--bg);
}

/* ---- Buttons -------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.6rem 1.25rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
    font-size: 0.9rem;
    border: none;
    transition: all var(--transition);
    white-space: nowrap;
}
.btn-primary {
    background: var(--primary);
    color: white;
}
.btn-primary:hover { background: var(--primary-dark); box-shadow: var(--shadow-md); }
.btn-secondary {
    background: var(--bg);
    color: var(--text);
    border: 1px solid var(--border);
}
.btn-secondary:hover { background: var(--border-light); }
.btn-success { background: var(--success); color: white; }
.btn-success:hover { background: #00A382; }
.btn-danger { background: var(--danger); color: white; }
.btn-danger:hover { background: #D45D43; }
.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 1.5px solid var(--primary);
}
.btn-outline:hover { background: var(--primary-bg); }
.btn-sm { padding: 0.4rem 0.8rem; font-size: 0.8rem; }
.btn-lg { padding: 0.8rem 1.75rem; font-size: 1rem; }
.btn-block { width: 100%; }

/* ---- Progress Bar --------------------------------------------------- */
.progress-bar-container {
    width: 100%;
    height: 8px;
    background: var(--border-light);
    border-radius: 4px;
    overflow: hidden;
}
.progress-bar-fill {
    height: 100%;
    border-radius: 4px;
    background: linear-gradient(90deg, var(--primary), var(--primary-light));
    transition: width 0.5s ease;
}
.progress-bar-fill.complete {
    background: linear-gradient(90deg, var(--success), #55EFC4);
}
.progress-text {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--primary);
    margin-top: 0.25rem;
}
.progress-text.complete { color: var(--success); }

/* ---- Dashboard ------------------------------------------------------ */
.dashboard-header {
    margin-bottom: 2rem;
}
.dashboard-header h1 {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 0.25rem;
}
.dashboard-header p {
    color: var(--text-secondary);
    font-size: 1rem;
}
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}
.stat-card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    padding: 1.5rem;
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
}
.stat-card .stat-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    margin-bottom: 0.75rem;
}
.stat-card .stat-icon.purple { background: var(--primary-bg); }
.stat-card .stat-icon.green { background: var(--success-bg); }
.stat-card .stat-icon.blue { background: var(--info-bg); }
.stat-card .stat-icon.orange { background: var(--warning-bg); }
.stat-card .stat-value {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text);
}
.stat-card .stat-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-top: 0.15rem;
}
.dashboard-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 1.5rem;
}

/* ---- Course Cards --------------------------------------------------- */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
}
.course-card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition);
    cursor: pointer;
    overflow: hidden;
}
.course-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-3px);
}
.course-card-thumb {
    height: 160px;
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: rgba(255, 255, 255, 0.7);
    position: relative;
}
.course-card-thumb .category-badge {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-xl);
    font-size: 0.75rem;
    font-weight: 600;
    background: rgba(255, 255, 255, 0.9);
    color: var(--primary);
}
.course-card-body {
    padding: 1.25rem;
}
.course-card-body h3 {
    font-size: 1.05rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text);
    line-height: 1.3;
}
.course-card-body p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}
.course-card-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: 0.75rem;
    font-size: 0.8rem;
    color: var(--text-light);
}
.course-card-meta span { display: flex; align-items: center; gap: 0.25rem; }
.course-card-footer {
    padding: 0.75rem 1.25rem;
    border-top: 1px solid var(--border-light);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

/* ---- Category Filters ----------------------------------------------- */
.filter-bar {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}
.filter-chip {
    padding: 0.4rem 1rem;
    border-radius: var(--radius-xl);
    border: 1px solid var(--border);
    background: var(--bg-card);
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}
.filter-chip:hover, .filter-chip.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* ---- Course Detail -------------------------------------------------- */
.course-detail-header {
    background: linear-gradient(135deg, var(--primary), var(--bg-sidebar));
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    color: white;
    margin-bottom: 2rem;
}
.course-detail-header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}
.course-detail-header .course-meta {
    display: flex;
    gap: 1.5rem;
    margin-top: 1rem;
    font-size: 0.9rem;
    opacity: 0.9;
}
.course-detail-header .course-meta span {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}
.module-tree { margin-top: 1rem; }
.module-item {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    margin-bottom: 0.75rem;
    overflow: hidden;
}
.module-header {
    padding: 1rem 1.25rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
    transition: background var(--transition);
}
.module-header:hover { background: var(--bg); }
.module-header h3 {
    font-size: 1rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.module-header .module-badge {
    font-size: 0.75rem;
    background: var(--primary-bg);
    color: var(--primary);
    padding: 0.15rem 0.5rem;
    border-radius: var(--radius-xl);
}
.lesson-list { border-top: 1px solid var(--border-light); }
.lesson-item {
    padding: 0.75rem 1.25rem 0.75rem 2.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid var(--border-light);
    cursor: pointer;
    transition: background var(--transition);
}
.lesson-item:last-child { border-bottom: none; }
.lesson-item:hover { background: var(--bg); }
.lesson-item .lesson-info {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}
.lesson-item .lesson-icon {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    background: var(--primary-bg);
    color: var(--primary);
}
.lesson-item .lesson-icon.completed {
    background: var(--success-bg);
    color: var(--success);
}
.lesson-item .lesson-title {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text);
}
.lesson-item .lesson-duration {
    font-size: 0.8rem;
    color: var(--text-light);
}

/* ---- Lesson Viewer -------------------------------------------------- */
.lesson-viewer {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 1.5rem;
}
.lesson-content-area {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    padding: 2rem;
}
.lesson-content-area h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}
.lesson-content-area .lesson-type-badge {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    margin-bottom: 1rem;
}
.lesson-type-badge.video { background: var(--info-bg); color: #0984E3; }
.lesson-type-badge.text { background: var(--primary-bg); color: var(--primary); }
.lesson-type-badge.quiz { background: var(--accent-light); color: var(--accent); }
.lesson-text-content {
    font-size: 0.95rem;
    line-height: 1.8;
    color: var(--text);
}
.lesson-text-content p { margin-bottom: 1rem; }
.lesson-video-placeholder {
    background: #1a1a2e;
    border-radius: var(--radius-md);
    height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 3rem;
    margin-bottom: 1rem;
}
.lesson-sidebar {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}
.lesson-nav-card {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    padding: 1.25rem;
}
.lesson-nav-card h4 {
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* ---- Quiz UI -------------------------------------------------------- */
.quiz-container {
    max-width: 800px;
    margin: 0 auto;
}
.quiz-header {
    background: linear-gradient(135deg, var(--accent), var(--primary));
    border-radius: var(--radius-lg);
    padding: 2rem;
    color: white;
    margin-bottom: 2rem;
    text-align: center;
}
.quiz-header h1 { font-size: 1.6rem; font-weight: 700; margin-bottom: 0.5rem; }
.quiz-header p { opacity: 0.9; }
.quiz-question {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    padding: 1.5rem;
    margin-bottom: 1.25rem;
}
.quiz-question .question-number {
    display: inline-block;
    background: var(--primary);
    color: white;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    text-align: center;
    line-height: 28px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-right: 0.5rem;
}
.quiz-question .question-text {
    font-size: 1rem;
    font-weight: 500;
    margin-bottom: 1rem;
    display: inline;
}
.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-top: 0.75rem;
}
.quiz-option {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-sm);
    border: 1.5px solid var(--border);
    cursor: pointer;
    transition: all var(--transition);
    font-size: 0.9rem;
}
.quiz-option:hover { border-color: var(--primary); background: var(--primary-bg); }
.quiz-option.selected { border-color: var(--primary); background: var(--primary-bg); }
.quiz-option.correct { border-color: var(--success); background: var(--success-bg); }
.quiz-option.incorrect { border-color: var(--danger); background: var(--danger-bg); }
.quiz-option .option-letter {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.8rem;
    flex-shrink: 0;
}
.quiz-option.selected .option-letter {
    background: var(--primary);
    color: white;
}
.quiz-results {
    background: var(--bg-card);
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    padding: 2rem;
    text-align: center;
}
.quiz-results .score-circle {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    font-size: 2rem;
    font-weight: 700;
}
.score-circle.passed {
    background: var(--success-bg);
    color: var(--success);
    border: 3px solid var(--success);
}
.score-circle.failed {
    background: var(--danger-bg);
    color: var(--danger);
    border: 3px solid var(--danger);
}
.quiz-explanation {
    background: var(--info-bg);
    border-radius: var(--radius-sm);
    padding: 0.75rem 1rem;
    margin-top: 0.75rem;
    font-size: 0.85rem;
    color: #0984E3;
    text-align: left;
}

/* ---- Toast ---------------------------------------------------------- */
.toast-container {
    position: fixed;
    top: 80px;
    right: 1.5rem;
    z-index: 1000;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}
.toast {
    padding: 0.75rem 1.25rem;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: var(--shadow-lg);
    animation: slideIn 0.3s ease;
    max-width: 400px;
}
.toast.success { background: var(--success); color: white; }
.toast.error { background: var(--danger); color: white; }
.toast.info { background: var(--primary); color: white; }
@keyframes slideIn {
    from { transform: translateX(100%); opacity: 0; }
    to { transform: translateX(0); opacity: 1; }
}

/* ---- Footer --------------------------------------------------------- */
.footer {
    background: var(--bg-card);
    border-top: 1px solid var(--border);
    padding: 1.5rem 2rem;
    text-align: center;
    margin-top: auto;
}
.footer-content p { font-size: 0.85rem; color: var(--text-secondary); }
.footer-tagline { margin-top: 0.25rem; font-style: italic; color: var(--text-light); }

/* ---- Empty State ---------------------------------------------------- */
.empty-state {
    text-align: center;
    padding: 3rem;
    color: var(--text-secondary);
}
.empty-state .empty-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}
.empty-state h3 {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text);
}

/* ---- Badge ---------------------------------------------------------- */
.badge {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: var(--radius-xl);
    font-size: 0.75rem;
    font-weight: 600;
}
.badge-primary { background: var(--primary-bg); color: var(--primary); }
.badge-success { background: var(--success-bg); color: var(--success); }
.badge-warning { background: var(--warning-bg); color: #E17055; }
.badge-info { background: var(--info-bg); color: #0984E3; }

/* ---- Responsive ----------------------------------------------------- */
@media (max-width: 768px) {
    .navbar { padding: 0 1rem; }
    .main-content { padding: 1rem; }
    .dashboard-grid { grid-template-columns: 1fr; }
    .lesson-viewer { grid-template-columns: 1fr; }
    .course-grid { grid-template-columns: 1fr; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .course-detail-header { padding: 1.5rem; }
    .course-detail-header h1 { font-size: 1.4rem; }
    .course-detail-header .course-meta { flex-wrap: wrap; gap: 0.75rem; }
}

@media (max-width: 480px) {
    .stats-grid { grid-template-columns: 1fr; }
    .filter-bar { gap: 0.35rem; }
    .filter-chip { padding: 0.3rem 0.75rem; font-size: 0.8rem; }
}