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

/* Skip-to-content link for accessibility */
.skip-link {
    position: absolute;
    top: -100%;
    left: 16px;
    background: var(--primary);
    color: #fff;
    padding: 12px 24px;
    border-radius: 0 0 8px 8px;
    z-index: 9999;
    font-weight: 600;
    text-decoration: none;
    transition: top 0.3s;
}

.skip-link:focus {
    top: 0;
}

:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --secondary: #8b5cf6;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --bg-light: #f8fafc;
    --bg-dark: #0f172a;
    --card-light: #ffffff;
    --card-dark: #1e293b;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-dark-primary: #f1f5f9;
    --text-dark-secondary: #94a3b8;
    --border-light: #e2e8f0;
    --border-dark: #334155;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-light);
    color: var(--text-primary);
    min-height: 100vh;
    transition: all 0.3s ease;
    -webkit-font-smoothing: antialiased;
}

body.dark-mode {
    background: var(--bg-dark);
    color: var(--text-dark-primary);
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    padding: 30px;
    border-radius: 20px;
    margin-bottom: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
    box-shadow: var(--shadow-lg);
}

.header-title h1 {
    font-size: 2rem;
    font-weight: 800;
    color: #fff;
    margin-bottom: 5px;
}

.header-title p {
    color: rgba(255, 255, 255, 0.9);
    font-size: 1rem;
}

.header-controls {
    display: flex;
    gap: 12px;
    align-items: center;
}

.user-badge {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    padding: 10px 20px;
    border-radius: 50px;
    color: #fff;
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    transition: all 0.3s;
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.user-badge:hover {
    background: rgba(255, 255, 255, 0.3);
}

.level-tag {
    background: linear-gradient(135deg, #fbbf24, #f59e0b);
    color: #1e293b;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 700;
}

.icon-btn {
    width: 44px;
    height: 44px;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: #fff;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: all 0.3s;
}

.icon-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

.notif-badge {
    position: absolute;
    top: -5px;
    right: -5px;
    width: 18px;
    height: 18px;
    background: var(--danger);
    border-radius: 50%;
    font-size: 0.7rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
}

/* Language Selector */
.lang-selector {
    display: flex;
    align-items: center;
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.3);
    padding: 0 12px;
    height: 44px;
    color: #fff;
    transition: all 0.3s;
    position: relative;
    cursor: pointer;
}

.lang-selector:hover {
    background: rgba(255, 255, 255, 0.3);
}

.lang-icon {
    margin-right: 8px;
    opacity: 0.9;
}

.lang-select {
    background: transparent;
    border: none;
    color: #fff;
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    outline: none;
    appearance: none;
    /* Hide default arrow */
    -webkit-appearance: none;
    padding-right: 18px;
}

/* Custom dropdown arrow using background image */
.lang-select {
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23FFFFFF%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: right center;
    background-size: 10px auto;
}

.lang-select option {
    background: var(--card-light);
    color: var(--text-primary);
    font-weight: 500;
}

body.dark-mode .lang-select option {
    background: var(--card-dark);
    color: var(--text-dark-primary);
}

/* Navigation Tabs */
.nav-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 30px;
    padding: 8px;
    background: var(--card-light);
    border-radius: 16px;
    box-shadow: var(--shadow);
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    flex-wrap: nowrap;
}

.nav-tabs::-webkit-scrollbar {
    display: none;
}

body.dark-mode .nav-tabs {
    background: var(--card-dark);
}

.nav-tab {
    padding: 12px 24px;
    border-radius: 12px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 0.95rem;
}

body.dark-mode .nav-tab {
    color: var(--text-dark-secondary);
}

.nav-tab:hover {
    background: var(--bg-light);
    color: var(--text-primary);
}

body.dark-mode .nav-tab:hover {
    background: var(--bg-dark);
    color: var(--text-dark-primary);
}

.nav-tab.active {
    background: var(--primary);
    color: #fff;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
    transform: translateY(-1px);
}

/* Cards */
.card {
    background: var(--card-light);
    border-radius: 16px;
    padding: 24px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-light);
    transition: all 0.3s;
}

body.dark-mode .card {
    background: var(--card-dark);
    border-color: var(--border-dark);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

/* Dashboard Grid */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    padding: 24px;
    border-radius: 16px;
    color: #fff;
    position: relative;
    overflow: hidden;
}

.stat-card::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    transform: rotate(45deg);
}

.stat-card.alt1 {
    background: linear-gradient(135deg, #ec4899, #f43f5e);
}

.stat-card.alt2 {
    background: linear-gradient(135deg, #06b6d4, #0ea5e9);
}

.stat-card.alt3 {
    background: linear-gradient(135deg, #10b981, #14b8a6);
}

.stat-label {
    font-size: 0.875rem;
    opacity: 0.9;
    margin-bottom: 8px;
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 800;
}

/* Progress Bar */
.progress-section {
    margin-bottom: 30px;
}

.progress-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 12px;
}

.progress-header h3 {
    font-size: 1rem;
    font-weight: 600;
}

.progress-bar {
    height: 12px;
    background: var(--border-light);
    border-radius: 6px;
    overflow: hidden;
}

body.dark-mode .progress-bar {
    background: var(--border-dark);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 6px;
    transition: width 0.5s ease;
}

/* Lessons Grid */
.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 20px;
}

.lesson-card {
    background: var(--card-light);
    border-radius: 16px;
    padding: 24px;
    border: 1px solid var(--border-light);
    cursor: pointer;
    transition: all 0.3s;
    border-left: 4px solid var(--primary);
    position: relative;
}

body.dark-mode .lesson-card {
    background: var(--card-dark);
    border-color: var(--border-dark);
    border-left-color: var(--primary);
}

.lesson-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.lesson-card.completed {
    border-left-color: var(--success);
}

.lesson-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.lesson-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
}

body.dark-mode .lesson-title {
    color: var(--text-dark-primary);
}

.lesson-status {
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.lesson-status.done {
    background: rgba(16, 185, 129, 0.1);
    color: var(--success);
}

.lesson-status.new {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning);
}

.lesson-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: 16px;
}

body.dark-mode .lesson-desc {
    color: var(--text-dark-secondary);
}

.lesson-meta {
    display: flex;
    gap: 16px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

body.dark-mode .lesson-meta {
    color: var(--text-dark-secondary);
}

.lesson-actions {
    display: flex;
    gap: 8px;
    margin-top: 16px;
}

.btn-fav {
    padding: 8px 16px;
    border-radius: 8px;
    border: 1px solid var(--border-light);
    background: transparent;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.3s;
    color: var(--text-secondary);
}

body.dark-mode .btn-fav {
    border-color: var(--border-dark);
    color: var(--text-dark-secondary);
}

.btn-fav:hover,
.btn-fav.active {
    background: var(--danger);
    color: #fff;
    border-color: var(--danger);
}

/* Search */
.search-box {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
}

.search-input {
    flex: 1;
    padding: 14px 20px;
    border: 2px solid var(--border-light);
    border-radius: 12px;
    font-size: 1rem;
    transition: all 0.3s;
    background: var(--card-light);
    color: var(--text-primary);
}

body.dark-mode .search-input {
    background: var(--card-dark);
    border-color: var(--border-dark);
    color: var(--text-dark-primary);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.btn-primary {
    padding: 14px 28px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.btn-secondary {
    padding: 14px 28px;
    background: var(--card-light);
    color: var(--text-primary);
    border: 2px solid var(--border-light);
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

body.dark-mode .btn-secondary {
    background: var(--card-dark);
    color: var(--text-dark-primary);
    border-color: var(--border-dark);
}

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

/* Tab Content */
.tab-content {
    display: none;
    animation: fadeIn 0.3s ease;
}

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

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Quiz */
.quiz-card {
    max-width: 800px;
    margin: 0 auto;
}

.quiz-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--border-light);
}

body.dark-mode .quiz-header {
    border-color: var(--border-dark);
}

.quiz-counter {
    background: var(--primary);
    color: #fff;
    padding: 8px 20px;
    border-radius: 20px;
    font-weight: 600;
}

.question {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 24px;
    line-height: 1.6;
}

.options {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.option {
    padding: 16px 20px;
    background: var(--bg-light);
    border: 2px solid var(--border-light);
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 1rem;
}

body.dark-mode .option {
    background: var(--bg-dark);
    border-color: var(--border-dark);
}

.option:hover {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.05);
}

.option.correct {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--success);
    color: var(--success);
}

.option.wrong {
    background: rgba(239, 68, 68, 0.1);
    border-color: var(--danger);
    color: var(--danger);
}

.result-box {
    text-align: center;
    padding: 40px;
}

.result-score {
    font-size: 4rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 16px;
}

.result-msg {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 30px;
}

body.dark-mode .result-msg {
    color: var(--text-dark-secondary);
}

.result-btns {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Notes */
.notes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

.note-card {
    padding: 20px;
    border-radius: 12px;
    position: relative;
    background: linear-gradient(135deg, #fef3c7, #fde68a);
}

.note-card.pink {
    background: linear-gradient(135deg, #fce7f3, #fbcfe8);
}

.note-card.blue {
    background: linear-gradient(135deg, #e0f2fe, #bae6fd);
}

.note-card.green {
    background: linear-gradient(135deg, #d1fae5, #a7f3d0);
}

.note-title {
    font-weight: 700;
    margin-bottom: 8px;
    color: #1e293b;
}

.note-text {
    font-size: 0.9rem;
    color: #475569;
    line-height: 1.5;
    margin-bottom: 12px;
}

.note-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.note-date {
    font-size: 0.8rem;
    color: #64748b;
}

.note-delete {
    background: rgba(0, 0, 0, 0.1);
    border: none;
    padding: 6px 12px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: all 0.3s;
}

.note-delete:hover {
    background: var(--danger);
    color: #fff;
}

/* Forum */
.forum-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.post-card {
    padding: 24px;
    background: var(--card-light);
    border-radius: 12px;
    border: 1px solid var(--border-light);
    border-left: 4px solid var(--primary);
}

body.dark-mode .post-card {
    background: var(--card-dark);
    border-color: var(--border-dark);
    border-left-color: var(--primary);
}

.post-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 12px;
}

.post-author {
    font-weight: 600;
    color: var(--primary);
}

.post-time {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

body.dark-mode .post-time {
    color: var(--text-dark-secondary);
}

.post-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.post-content {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 16px;
}

body.dark-mode .post-content {
    color: var(--text-dark-secondary);
}

.post-actions {
    display: flex;
    gap: 16px;
}

.post-action {
    color: var(--primary);
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s;
}

.post-action:hover {
    color: var(--primary-dark);
}

/* Leaderboard */
.leaderboard-table {
    width: 100%;
    border-collapse: collapse;
}

.leaderboard-table thead {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff;
}

.leaderboard-table th,
.leaderboard-table td {
    padding: 16px;
    text-align: left;
}

.leaderboard-table tbody tr {
    border-bottom: 1px solid var(--border-light);
    transition: all 0.3s;
}

body.dark-mode .leaderboard-table tbody tr {
    border-color: var(--border-dark);
}

.leaderboard-table tbody tr:hover {
    background: var(--bg-light);
}

body.dark-mode .leaderboard-table tbody tr:hover {
    background: var(--bg-dark);
}

.rank {
    font-weight: 700;
}

.rank-1 {
    color: #fbbf24;
    font-size: 1.2rem;
}

.rank-2 {
    color: #94a3b8;
}

.rank-3 {
    color: #d97706;
}

/* Certificate */
.certificate {
    max-width: 700px;
    margin: 30px auto;
    padding: 50px;
    background: linear-gradient(135deg, #fef3c7, #fde68a);
    border: 8px double #d97706;
    border-radius: 8px;
    text-align: center;
}

.cert-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: #92400e;
    margin-bottom: 30px;
    text-transform: uppercase;
    letter-spacing: 3px;
}

.cert-text {
    font-size: 1.1rem;
    color: #78350f;
    margin-bottom: 16px;
}

.cert-name {
    font-size: 1.8rem;
    font-weight: 700;
    color: #1e293b;
    border-bottom: 2px solid #92400e;
    padding-bottom: 10px;
    margin: 30px 0;
    display: inline-block;
}

.cert-date {
    font-size: 0.9rem;
    color: #92400e;
    margin-top: 30px;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--card-light);
    padding: 32px;
    border-radius: 20px;
    max-width: 500px;
    width: 90%;
    position: relative;
    animation: slideUp 0.3s ease;
}

body.dark-mode .modal-content {
    background: var(--card-dark);
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-close {
    position: absolute;
    top: 16px;
    right: 16px;
    width: 32px;
    height: 32px;
    border-radius: 8px;
    border: none;
    background: var(--bg-light);
    cursor: pointer;
    font-size: 1.2rem;
}

body.dark-mode .modal-close {
    background: var(--bg-dark);
    color: var(--text-dark-primary);
}

.modal-title {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 24px;
    color: var(--primary);
}

.form-group {
    margin-bottom: 16px;
}

.form-label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}

.form-input,
.form-textarea {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-light);
    border-radius: 10px;
    font-size: 1rem;
    transition: all 0.3s;
    background: var(--card-light);
    color: var(--text-primary);
}

body.dark-mode .form-input,
body.dark-mode .form-textarea {
    background: var(--bg-dark);
    border-color: var(--border-dark);
    color: var(--text-dark-primary);
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary);
}

.form-textarea {
    min-height: 120px;
    resize: vertical;
    font-family: inherit;
}

.modal-btns {
    display: flex;
    gap: 12px;
    margin-top: 24px;
}

.modal-btns .btn-primary,
.modal-btns .btn-secondary {
    flex: 1;
}

/* Notification */
.notification {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 16px 24px;
    border-radius: 12px;
    background: var(--card-light);
    box-shadow: var(--shadow-lg);
    z-index: 2000;
    animation: slideIn 0.3s ease;
    max-width: 400px;
    transition: opacity 0.3s ease;
}

.notification:nth-child(2) { top: 90px; }
.notification:nth-child(3) { top: 160px; }

body.dark-mode .notification {
    background: var(--card-dark);
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(100px);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.notification.success {
    border-left: 4px solid var(--success);
}

.notification.warning {
    border-left: 4px solid var(--warning);
}

.notification.error {
    border-left: 4px solid var(--danger);
}

/* Section Title */
.section-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--text-primary);
}

body.dark-mode .section-title {
    color: var(--text-dark-primary);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

/* Footer */
.footer {
    text-align: center;
    padding: 40px 20px;
    margin-top: 60px;
    border-top: 1px solid var(--border-light);
}

body.dark-mode .footer {
    border-color: var(--border-dark);
}

.footer-quote {
    font-style: italic;
    color: var(--text-secondary);
    margin-bottom: 8px;
    font-size: 1rem;
}

body.dark-mode .footer-quote {
    color: var(--text-dark-secondary);
}

.footer-author {
    font-weight: 600;
    margin-bottom: 24px;
}

.footer-info {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

body.dark-mode .footer-info {
    color: var(--text-dark-secondary);
}

.footer-info p {
    margin-bottom: 4px;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

body.dark-mode .empty-state {
    color: var(--text-dark-secondary);
}

.empty-state p {
    font-size: 1rem;
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 12px;
    }

    .header {
        padding: 24px 20px;
        flex-direction: column;
        text-align: center;
        gap: 16px;
        border-radius: 16px;
    }

    .header-controls {
        width: 100%;
        justify-content: center;
    }

    .header-title h1 {
        font-size: 1.6rem;
    }

    .nav-tabs {
        justify-content: flex-start;
        padding: 6px;
        border-radius: 12px;
    }

    .nav-tab {
        padding: 10px 18px;
        font-size: 0.9rem;
        white-space: nowrap;
    }

    .lessons-grid {
        grid-template-columns: 1fr;
    }

    .dashboard-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .stat-value {
        font-size: 2rem;
    }

    .section-title {
        font-size: 1.15rem;
    }
}

@media (max-width: 480px) {
    .dashboard-grid {
        grid-template-columns: 1fr;
    }

    .search-box {
        flex-direction: column;
        gap: 8px;
    }

    .result-btns {
        flex-direction: column;
    }

    .stat-card {
        padding: 20px;
    }
}

/* === Phase 6: Achievement Badges === */
.badges-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 16px;
}

.badge-card {
    text-align: center;
    padding: 20px 12px;
    border-radius: 16px;
    background: var(--bg-light);
    border: 2px solid transparent;
    transition: all 0.3s ease;
}

body.dark-mode .badge-card {
    background: var(--card-dark);
}

.badge-card.unlocked {
    border-color: var(--accent);
    box-shadow: 0 0 20px rgba(245, 158, 11, 0.15);
}

.badge-card.unlocked .badge-icon {
    animation: badgePulse 2s ease-in-out infinite;
}

.badge-card.locked {
    opacity: 0.45;
    filter: grayscale(1);
}

.badge-icon {
    font-size: 40px;
    margin-bottom: 8px;
}

.badge-name {
    font-weight: 700;
    font-size: 0.85rem;
    margin-bottom: 4px;
    color: var(--text-primary);
}

body.dark-mode .badge-name {
    color: var(--text-dark-primary);
}

.badge-desc {
    font-size: 0.75rem;
    color: var(--text-secondary);
    line-height: 1.4;
}

body.dark-mode .badge-desc {
    color: var(--text-dark-secondary);
}

@keyframes badgePulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.1); }
}

/* === Phase 6: Forum Replies === */
.post-replies {
    display: none;
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid rgba(99, 102, 241, 0.15);
}

.post-replies.show {
    display: block;
    animation: fadeSlideIn 0.3s ease;
}

@keyframes fadeSlideIn {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
}

.reply-card {
    padding: 10px 14px;
    margin-bottom: 8px;
    background: var(--bg-light);
    border-radius: 10px;
    border-left: 3px solid var(--primary);
}

body.dark-mode .reply-card {
    background: rgba(255, 255, 255, 0.04);
}

.reply-author {
    font-weight: 600;
    font-size: 0.82rem;
    color: var(--primary);
    margin-right: 8px;
}

.reply-date {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

body.dark-mode .reply-date {
    color: var(--text-dark-secondary);
}

.reply-text {
    margin-top: 6px;
    font-size: 0.88rem;
    color: var(--text-primary);
    line-height: 1.5;
}

body.dark-mode .reply-text {
    color: var(--text-dark-primary);
}

/* === Phase 6: Note Edit Button === */
.note-actions-group {
    display: flex;
    gap: 8px;
}

.note-edit {
    background: none;
    border: none;
    color: var(--primary);
    font-size: 0.8rem;
    cursor: pointer;
    font-weight: 600;
    padding: 4px 8px;
    border-radius: 6px;
    transition: background 0.2s;
}

.note-edit:hover {
    background: rgba(99, 102, 241, 0.1);
}

/* =========================================================
   Visual refresh — Aurora Study Space
   Pure CSS enhancement: no extra dependencies required.
   ========================================================= */
:root {
    --primary: #6d5dfc;
    --primary-dark: #5546e8;
    --secondary: #a855f7;
    --accent: #22d3ee;
    --bg-light: #f4f7ff;
    --card-light: rgba(255, 255, 255, 0.84);
    --border-light: rgba(148, 163, 184, 0.22);
    --shadow: 0 12px 30px rgba(67, 56, 202, 0.08);
    --shadow-lg: 0 24px 60px rgba(67, 56, 202, 0.16);
}

html {
    scroll-behavior: smooth;
}

body {
    position: relative;
    overflow-x: hidden;
    background:
        radial-gradient(circle at 8% 5%, rgba(129, 140, 248, 0.18), transparent 28rem),
        radial-gradient(circle at 92% 10%, rgba(34, 211, 238, 0.12), transparent 26rem),
        var(--bg-light);
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    z-index: -2;
    pointer-events: none;
    opacity: 0.42;
    background-image:
        linear-gradient(rgba(99, 102, 241, 0.045) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99, 102, 241, 0.045) 1px, transparent 1px);
    background-size: 42px 42px;
    mask-image: linear-gradient(to bottom, black, transparent 75%);
}

body::after {
    content: '';
    position: fixed;
    width: 420px;
    height: 420px;
    top: 24%;
    right: -250px;
    z-index: -1;
    pointer-events: none;
    border-radius: 50%;
    background: rgba(168, 85, 247, 0.12);
    filter: blur(90px);
    animation: ambientDrift 14s ease-in-out infinite alternate;
}

body.dark-mode {
    --bg-dark: #090d1c;
    --card-dark: rgba(19, 27, 52, 0.82);
    --border-dark: rgba(148, 163, 184, 0.18);
    --shadow: 0 16px 40px rgba(0, 0, 0, 0.24);
    --shadow-lg: 0 26px 70px rgba(0, 0, 0, 0.38);
    background:
        radial-gradient(circle at 8% 5%, rgba(109, 93, 252, 0.2), transparent 28rem),
        radial-gradient(circle at 92% 10%, rgba(34, 211, 238, 0.1), transparent 26rem),
        var(--bg-dark);
}

body.dark-mode::before {
    opacity: 0.22;
}

.container {
    position: relative;
    z-index: 0;
    padding-top: 28px;
}

.header {
    position: relative;
    isolation: isolate;
    min-height: 190px;
    overflow: hidden;
    padding: 36px 40px;
    border: 1px solid rgba(255, 255, 255, 0.22);
    border-radius: 28px;
    background:
        radial-gradient(circle at 86% 10%, rgba(34, 211, 238, 0.28), transparent 18rem),
        radial-gradient(circle at 12% 120%, rgba(244, 114, 182, 0.22), transparent 20rem),
        linear-gradient(120deg, #4f46e5 0%, #7c3aed 52%, #9333ea 100%);
    box-shadow: 0 26px 70px rgba(79, 70, 229, 0.28);
    animation: headerReveal 0.75s cubic-bezier(.22, 1, .36, 1) both;
}

.header::before,
.header::after {
    content: '';
    position: absolute;
    pointer-events: none;
    z-index: -1;
}

.header::before {
    width: 280px;
    height: 280px;
    top: -155px;
    right: 16%;
    border: 1px solid rgba(255, 255, 255, 0.18);
    border-radius: 42% 58% 65% 35%;
    transform: rotate(28deg);
    box-shadow:
        0 0 0 24px rgba(255, 255, 255, 0.035),
        0 0 0 48px rgba(255, 255, 255, 0.025);
    animation: orbitShape 16s linear infinite;
}

.header::after {
    inset: 0;
    opacity: 0.32;
    background: linear-gradient(115deg, transparent 20%, rgba(255, 255, 255, 0.28) 48%, transparent 68%);
    transform: translateX(-120%);
    animation: headerSheen 7s ease-in-out 1.2s infinite;
}

.header-title {
    max-width: 650px;
}

.header-title h1 {
    letter-spacing: -0.045em;
    text-shadow: 0 8px 22px rgba(30, 27, 75, 0.2);
    animation: titleRise 0.7s 0.12s both;
}

.header-title p {
    animation: titleRise 0.7s 0.22s both;
}

.header-controls {
    animation: titleRise 0.7s 0.3s both;
}

.user-badge,
.lang-selector,
.icon-btn {
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

.user-badge:hover,
.lang-selector:hover,
.icon-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 24px rgba(30, 27, 75, 0.16), inset 0 1px 0 rgba(255, 255, 255, 0.28);
}

.nav-tabs {
    position: sticky;
    top: 14px;
    z-index: 20;
    border: 1px solid var(--border-light);
    background: color-mix(in srgb, var(--card-light) 86%, transparent);
    backdrop-filter: blur(18px);
    -webkit-backdrop-filter: blur(18px);
    box-shadow: 0 12px 34px rgba(67, 56, 202, 0.1);
}

body.dark-mode .nav-tabs {
    background: color-mix(in srgb, var(--card-dark) 88%, transparent);
}

.nav-tab {
    position: relative;
    overflow: hidden;
}

.nav-tab::after {
    content: '';
    position: absolute;
    left: 22px;
    right: 22px;
    bottom: 5px;
    height: 2px;
    border-radius: 99px;
    background: currentColor;
    transform: scaleX(0);
    transform-origin: center;
    transition: transform 0.3s ease;
}

.nav-tab:hover::after,
.nav-tab.active::after {
    transform: scaleX(1);
}

.card,
.lesson-card,
.post-card,
.note-card,
.stat-card {
    will-change: transform;
}

.card {
    background: var(--card-light);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    box-shadow: var(--shadow);
}

body.dark-mode .card {
    background: var(--card-dark);
}

.card:hover {
    border-color: rgba(109, 93, 252, 0.32);
}

.dashboard-grid > .stat-card,
.lessons-grid > .lesson-card,
.notes-grid > .note-card,
.forum-list > .post-card,
.badges-grid > .badge-card {
    animation: itemReveal 0.6s cubic-bezier(.22, 1, .36, 1) both;
}

.dashboard-grid > :nth-child(2),
.lessons-grid > :nth-child(2),
.notes-grid > :nth-child(2),
.forum-list > :nth-child(2),
.badges-grid > :nth-child(2) {
    animation-delay: 0.06s;
}

.dashboard-grid > :nth-child(3),
.lessons-grid > :nth-child(3),
.notes-grid > :nth-child(3),
.forum-list > :nth-child(3),
.badges-grid > :nth-child(3) {
    animation-delay: 0.12s;
}

.dashboard-grid > :nth-child(4),
.lessons-grid > :nth-child(4),
.notes-grid > :nth-child(4),
.forum-list > :nth-child(4),
.badges-grid > :nth-child(4) {
    animation-delay: 0.18s;
}

.stat-card {
    min-height: 138px;
    border: 1px solid rgba(255, 255, 255, 0.18);
    box-shadow: 0 16px 32px rgba(67, 56, 202, 0.16);
    transition: transform 0.35s ease, box-shadow 0.35s ease;
}

.stat-card:hover {
    transform: translateY(-7px) rotate(-0.5deg);
    box-shadow: 0 22px 42px rgba(67, 56, 202, 0.22);
}

.stat-card::before {
    animation: statGlow 6s ease-in-out infinite alternate;
}

.stat-value {
    letter-spacing: -0.06em;
    text-shadow: 0 4px 14px rgba(30, 27, 75, 0.16);
}

.progress-section.card {
    overflow: hidden;
}

.progress-bar {
    position: relative;
    height: 14px;
    border: 1px solid rgba(148, 163, 184, 0.12);
}

.progress-fill {
    position: relative;
    overflow: hidden;
    background: linear-gradient(90deg, #6d5dfc, #a855f7 52%, #22d3ee);
    box-shadow: 0 0 18px rgba(109, 93, 252, 0.4);
}

.progress-fill::after {
    content: '';
    position: absolute;
    inset: 0;
    width: 45%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.6), transparent);
    transform: translateX(-120%);
    animation: progressSheen 2.4s ease-in-out infinite;
}

.lesson-card {
    overflow: hidden;
    background: var(--card-light);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: var(--shadow);
}

body.dark-mode .lesson-card {
    background: var(--card-dark);
}

.lesson-card::after {
    content: '';
    position: absolute;
    width: 110px;
    height: 110px;
    right: -48px;
    bottom: -50px;
    border-radius: 50%;
    background: rgba(109, 93, 252, 0.08);
    transition: transform 0.4s ease, background 0.4s ease;
}

.lesson-card:hover::after {
    transform: scale(2.5);
    background: rgba(109, 93, 252, 0.14);
}

.lesson-card.completed {
    border-left-color: var(--success);
}

.lesson-title {
    letter-spacing: -0.02em;
}

.btn-primary,
.btn-secondary,
.btn-fav {
    position: relative;
    overflow: hidden;
}

.btn-primary::after,
.btn-secondary::after,
.btn-fav::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(105deg, transparent 35%, rgba(255, 255, 255, 0.3) 50%, transparent 65%);
    transform: translateX(-120%);
    transition: transform 0.55s ease;
}

.btn-primary:hover::after,
.btn-secondary:hover::after,
.btn-fav:hover::after {
    transform: translateX(120%);
}

.btn-primary:active,
.btn-secondary:active,
.btn-fav:active,
.icon-btn:active {
    transform: scale(0.97);
}

.search-box {
    padding: 8px;
    border: 1px solid var(--border-light);
    border-radius: 18px;
    background: color-mix(in srgb, var(--card-light) 75%, transparent);
    box-shadow: var(--shadow);
}

body.dark-mode .search-box {
    background: color-mix(in srgb, var(--card-dark) 82%, transparent);
}

.search-input {
    border-color: transparent;
    background: transparent;
}

.search-input:focus {
    background: var(--card-light);
}

body.dark-mode .search-input:focus {
    background: var(--card-dark);
}

.tab-content.active {
    animation: contentReveal 0.45s cubic-bezier(.22, 1, .36, 1) both;
}

.option {
    position: relative;
    overflow: hidden;
}

.option::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--primary);
    transform: scaleY(0);
    transition: transform 0.25s ease;
}

.option:hover::before,
.option:focus-visible::before {
    transform: scaleY(1);
}

.note-card,
.post-card {
    box-shadow: var(--shadow);
    transition: transform 0.35s ease, box-shadow 0.35s ease;
}

.note-card:hover,
.post-card:hover {
    transform: translateY(-6px) rotate(0.35deg);
    box-shadow: var(--shadow-lg);
}

.badge-card {
    position: relative;
    overflow: hidden;
}

.badge-card.unlocked {
    background:
        radial-gradient(circle at 50% 0%, rgba(245, 158, 11, 0.14), transparent 65%),
        var(--bg-light);
}

.badge-card.unlocked::after {
    content: '✦';
    position: absolute;
    top: 8px;
    right: 12px;
    color: #f59e0b;
    animation: sparkle 2.2s ease-in-out infinite;
}

body.dark-mode .badge-card.unlocked {
    background:
        radial-gradient(circle at 50% 0%, rgba(245, 158, 11, 0.16), transparent 65%),
        var(--card-dark);
}

.modal {
    background: rgba(15, 23, 42, 0.64);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.modal-content {
    border: 1px solid var(--border-light);
    box-shadow: 0 30px 90px rgba(15, 23, 42, 0.3);
}

.notification {
    border: 1px solid var(--border-light);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
}

:focus-visible {
    outline: 3px solid rgba(34, 211, 238, 0.7);
    outline-offset: 3px;
}

@keyframes headerReveal {
    from { opacity: 0; transform: translateY(-18px) scale(0.98); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes titleRise {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes itemReveal {
    from { opacity: 0; transform: translateY(14px) scale(0.985); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes contentReveal {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes headerSheen {
    0%, 35% { transform: translateX(-120%); }
    65%, 100% { transform: translateX(120%); }
}

@keyframes orbitShape {
    from { transform: rotate(28deg) translate3d(0, 0, 0); }
    to { transform: rotate(388deg) translate3d(12px, 8px, 0); }
}

@keyframes ambientDrift {
    from { transform: translate3d(0, 0, 0) scale(1); }
    to { transform: translate3d(-90px, 40px, 0) scale(1.18); }
}

@keyframes statGlow {
    from { transform: translate(0, 0) rotate(45deg); opacity: 0.75; }
    to { transform: translate(-18px, 14px) rotate(65deg); opacity: 1; }
}

@keyframes progressSheen {
    0%, 25% { transform: translateX(-120%); }
    70%, 100% { transform: translateX(300%); }
}

@keyframes sparkle {
    0%, 100% { opacity: 0.35; transform: scale(0.8) rotate(0deg); }
    50% { opacity: 1; transform: scale(1.2) rotate(18deg); }
}

@media (max-width: 768px) {
    .container {
        padding-top: 14px;
    }

    .header {
        min-height: 0;
        padding: 28px 22px;
        border-radius: 22px;
    }

    .nav-tabs {
        top: 8px;
    }

    .search-box {
        padding: 6px;
    }
}

/* === Cross-device fit: phone, tablet, Windows desktop === */
html {
    width: 100%;
    overflow-x: hidden;
    -webkit-text-size-adjust: 100%;
    text-size-adjust: 100%;
}

body {
    width: 100%;
    overflow-x: hidden;
}

.container,
main,
.tab-content,
.card,
.lesson-card,
.note-card,
.post-card {
    min-width: 0;
}

.header-title,
.header-controls,
.section-header,
.lesson-header,
.lesson-meta,
.lesson-actions {
    min-width: 0;
}

.header-controls {
    flex-wrap: wrap;
}

.lang-select {
    min-width: 0;
    max-width: min(240px, 34vw);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.nav-tab,
button,
select,
input,
textarea {
    touch-action: manipulation;
}

button,
.nav-tab,
.icon-btn {
    min-height: 44px;
}

.lesson-title,
.post-title,
.note-title,
.section-title,
.question,
.modal-title {
    overflow-wrap: anywhere;
}

.lesson-meta {
    flex-wrap: wrap;
}

.lesson-actions,
.result-btns,
.modal-btns {
    flex-wrap: wrap;
}

.modal {
    padding: 12px;
}

.modal-content {
    width: min(100%, 500px);
    max-height: calc(100vh - 24px);
    max-height: calc(100dvh - 24px);
    overflow-y: auto;
    overscroll-behavior: contain;
}

.notification {
    right: max(12px, env(safe-area-inset-right));
    left: max(12px, env(safe-area-inset-left));
    width: auto;
    max-width: none;
}

@media (max-width: 768px) {
    .container {
        width: 100%;
        padding-top: 14px;
        padding-right: max(12px, env(safe-area-inset-right));
        padding-bottom: max(20px, env(safe-area-inset-bottom));
        padding-left: max(12px, env(safe-area-inset-left));
    }

    .header {
        width: 100%;
        padding: 24px 18px;
    }

    .header-title {
        width: 100%;
    }

    .header-title h1 {
        font-size: clamp(1.45rem, 6vw, 1.8rem);
        line-height: 1.15;
    }

    .header-title p {
        font-size: clamp(0.82rem, 3.5vw, 1rem);
        line-height: 1.45;
    }

    .header-controls {
        width: 100%;
        gap: 8px;
    }

    .user-badge {
        max-width: 100%;
        min-width: 0;
    }

    .nav-tabs {
        top: max(8px, env(safe-area-inset-top));
        max-width: 100%;
        margin-bottom: 22px;
        scrollbar-width: none;
    }

    .nav-tab {
        flex: 0 0 auto;
        padding: 10px 16px;
    }

    .card,
    .lesson-card,
    .post-card {
        padding: 20px;
    }

    .section-header {
        align-items: stretch;
        flex-wrap: wrap;
        gap: 12px;
    }

    .section-header .section-title {
        flex: 1 1 100%;
    }

    .section-header > button {
        width: 100%;
    }

    .lessons-grid,
    .notes-grid {
        grid-template-columns: minmax(0, 1fr);
    }

    .lesson-card,
    .note-card,
    .post-card {
        overflow-wrap: anywhere;
    }

    .search-input {
        min-width: 0;
        width: 100%;
    }

    .search-box .btn-primary,
    .result-btns > button,
    .modal-btns > button {
        min-width: 140px;
    }
}

@media (max-width: 600px) {
    .header-controls {
        display: grid;
        grid-template-columns: minmax(0, 1fr) auto auto;
        width: 100%;
    }

    .user-badge {
        grid-column: 1 / -1;
        justify-content: center;
        width: 100%;
    }

    .lang-selector {
        width: 100%;
        min-width: 0;
        justify-content: center;
    }

    .lang-select {
        width: 100%;
        max-width: none;
    }

    .icon-btn {
        width: 44px;
        flex: 0 0 44px;
    }

    .lesson-header {
        gap: 8px;
    }

    .lesson-title {
        flex: 1 1 100%;
    }

    .lesson-status {
        width: fit-content;
    }

    .lesson-actions,
    .result-btns,
    .modal-btns {
        flex-direction: column;
        align-items: stretch;
    }

    .lesson-actions > *,
    .result-btns > *,
    .modal-btns > * {
        width: 100%;
    }

    .result-box {
        padding: 28px 8px;
    }

    .result-score {
        font-size: clamp(2.8rem, 14vw, 4rem);
    }
}

@media (max-width: 380px) {
    .container {
        padding-right: 8px;
        padding-left: 8px;
    }

    .header {
        padding: 20px 14px;
        border-radius: 20px;
    }

    .nav-tabs {
        padding: 5px;
    }

    .nav-tab {
        padding: 9px 13px;
        font-size: 0.82rem;
    }

    .card,
    .lesson-card,
    .post-card {
        padding: 16px;
    }

    .lang-select {
        font-size: 0.78rem;
    }
}

@media (hover: none) {
    .card:hover,
    .lesson-card:hover,
    .note-card:hover,
    .post-card:hover,
    .stat-card:hover {
        transform: none;
    }
}

/* === Header identity polish === */
.header-title {
    position: relative;
    z-index: 1;
}

.header-title h1 {
    display: inline-block;
    font-size: clamp(2rem, 4vw, 3rem);
    line-height: 1.05;
    letter-spacing: -0.055em;
    background: linear-gradient(
        110deg,
        #ffffff 0%,
        #e0e7ff 32%,
        #a5f3fc 58%,
        #ffffff 82%,
        #ddd6fe 100%
    );
    background-size: 220% auto;
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    text-shadow: 0 10px 28px rgba(30, 27, 75, 0.18);
    animation:
        titleRise 0.7s 0.12s both,
        titleShimmer 7s 1s ease-in-out infinite;
}

.header-title p {
    max-width: 38rem;
    margin-top: 12px;
    color: rgba(255, 255, 255, 0.88);
    font-size: clamp(0.9rem, 1.8vw, 1.05rem);
    line-height: 1.55;
    letter-spacing: 0.01em;
}

.user-badge {
    position: relative;
    isolation: isolate;
    overflow: hidden;
    min-width: 138px;
    padding: 11px 14px 11px 16px;
    gap: 9px;
    border-color: rgba(255, 255, 255, 0.42);
    background: linear-gradient(
        135deg,
        rgba(255, 255, 255, 0.25),
        rgba(255, 255, 255, 0.11)
    );
    box-shadow:
        0 10px 24px rgba(30, 27, 75, 0.14),
        inset 0 1px 0 rgba(255, 255, 255, 0.3);
    animation: userBadgeReveal 0.75s 0.32s both;
}

.user-badge::before {
    content: '';
    width: 10px;
    height: 10px;
    flex: 0 0 10px;
    border-radius: 50%;
    background: #86efac;
    box-shadow:
        0 0 0 4px rgba(134, 239, 172, 0.16),
        0 0 18px rgba(134, 239, 172, 0.9);
    animation: onlinePulse 2.2s ease-in-out infinite;
}

.user-badge::after {
    content: '';
    position: absolute;
    inset: 0;
    z-index: -1;
    background: linear-gradient(
        115deg,
        transparent 25%,
        rgba(255, 255, 255, 0.3) 48%,
        transparent 70%
    );
    transform: translateX(-125%);
    animation: badgeSheen 5.5s 1.4s ease-in-out infinite;
}

.user-badge #userName {
    min-width: 0;
    max-width: 12rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-weight: 700;
    letter-spacing: 0.01em;
}

.level-tag {
    position: relative;
    overflow: hidden;
    padding: 5px 10px;
    border: 1px solid rgba(255, 255, 255, 0.45);
    box-shadow:
        0 5px 14px rgba(245, 158, 11, 0.24),
        inset 0 1px 0 rgba(255, 255, 255, 0.55);
    animation: levelFloat 3s ease-in-out infinite;
}

.level-tag::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(
        105deg,
        transparent 30%,
        rgba(255, 255, 255, 0.7) 50%,
        transparent 70%
    );
    transform: translateX(-130%);
    animation: levelSheen 4s 1.8s ease-in-out infinite;
}

@keyframes titleShimmer {
    0%,
    68%,
    100% {
        background-position: 0% center;
    }

    82% {
        background-position: 100% center;
    }
}

@keyframes userBadgeReveal {
    from {
        opacity: 0;
        transform: translateY(10px) scale(0.96);
    }

    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@keyframes onlinePulse {
    0%,
    100% {
        transform: scale(0.9);
        opacity: 0.75;
    }

    50% {
        transform: scale(1.12);
        opacity: 1;
    }
}

@keyframes badgeSheen {
    0%,
    25% {
        transform: translateX(-125%);
    }

    55%,
    100% {
        transform: translateX(125%);
    }
}

@keyframes levelFloat {
    0%,
    100% {
        transform: translateY(0) rotate(0deg);
    }

    50% {
        transform: translateY(-2px) rotate(-1deg);
    }
}

@keyframes levelSheen {
    0%,
    35% {
        transform: translateX(-130%);
    }

    65%,
    100% {
        transform: translateX(130%);
    }
}

@media (max-width: 600px) {
    .header-title h1 {
        font-size: clamp(1.8rem, 10vw, 2.4rem);
    }

    .header-title p {
        margin-top: 9px;
    }

    .user-badge {
        min-width: 0;
    }
}

/* === Certificate preview and A4 landscape export === */
.certificate-preview {
    width: 100%;
    max-width: 1120px;
    margin: 30px auto;
    padding: 4px;
    overflow-x: auto;
    overscroll-behavior-x: contain;
}

.certificate-pdf {
    position: relative;
    width: 1120px;
    height: 730px;
    box-sizing: border-box;
    padding: 14px;
    overflow: hidden;
    break-inside: avoid;
    page-break-inside: avoid;
    color: #172b4d;
    background: #f7f2e8;
    box-shadow: 0 24px 70px rgba(15, 23, 42, 0.2);
    font-family: 'Inter', Arial, sans-serif;
}

.certificate-frame {
    width: 100%;
    height: 100%;
    box-sizing: border-box;
    padding: 10px;
    background: #132d4f;
}

.certificate-inner {
    position: relative;
    display: flex;
    flex-direction: column;
    width: 100%;
    height: 100%;
    box-sizing: border-box;
    overflow: hidden;
    padding: 30px 52px 22px;
    border: 2px solid #caa94d;
    background:
        radial-gradient(circle at 50% 38%, rgba(202, 169, 77, 0.11), transparent 26%),
        linear-gradient(135deg, #fffdf7 0%, #f7f2e8 100%);
}

.certificate-inner::before,
.certificate-inner::after {
    content: '✦';
    position: absolute;
    z-index: 0;
    color: rgba(202, 169, 77, 0.5);
    font-size: 25px;
}

.certificate-inner::before {
    top: 16px;
    left: 18px;
}

.certificate-inner::after {
    right: 18px;
    bottom: 12px;
}

.certificate-watermark {
    position: absolute;
    z-index: 0;
    top: 42%;
    left: 50%;
    color: rgba(19, 45, 79, 0.035);
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 230px;
    font-weight: 800;
    line-height: 1;
    transform: translate(-50%, -50%);
    pointer-events: none;
}

.certificate-brand,
.certificate-heading,
.certificate-recipient,
.certificate-details,
.certificate-footer {
    position: relative;
    z-index: 1;
}

.certificate-brand {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    margin-bottom: 14px;
    text-align: left;
}

.certificate-brand-mark {
    display: grid;
    width: 42px;
    height: 42px;
    place-items: center;
    border: 2px solid #caa94d;
    border-radius: 12px;
    color: #fffdf7;
    background: #132d4f;
    font-size: 14px;
    font-weight: 800;
    letter-spacing: 1px;
    box-shadow: 0 5px 12px rgba(19, 45, 79, 0.14);
}

.certificate-brand-name {
    color: #132d4f;
    font-size: 17px;
    font-weight: 800;
    letter-spacing: 2px;
    text-transform: uppercase;
}

.certificate-brand-subtitle {
    margin-top: 3px;
    color: #8b7b58;
    font-size: 9px;
    letter-spacing: 2px;
    text-transform: uppercase;
}

.certificate-heading {
    text-align: center;
}

.certificate-kicker {
    color: #8b7b58;
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 4px;
}

.certificate-heading h1 {
    margin: 3px 0 0;
    color: #132d4f;
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 50px;
    font-weight: 600;
    letter-spacing: 7px;
    line-height: 1.05;
    text-transform: uppercase;
}

.certificate-heading-subtitle {
    margin-top: 4px;
    color: #c39b35;
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 17px;
    font-style: italic;
    letter-spacing: 3px;
}

.certificate-heading-line {
    display: flex;
    align-items: center;
    gap: 12px;
    width: 240px;
    margin: 11px auto 0;
    color: #caa94d;
    font-size: 15px;
}

.certificate-heading-line::before,
.certificate-heading-line::after {
    content: '';
    flex: 1;
    height: 1px;
    background: linear-gradient(90deg, transparent, #caa94d);
}

.certificate-heading-line::after {
    background: linear-gradient(90deg, #caa94d, transparent);
}

.certificate-recipient {
    margin-top: 15px;
    text-align: center;
}

.certificate-eyebrow {
    margin: 0;
    color: #68758a;
    font-size: 12px;
    letter-spacing: 1.5px;
}

.certificate-recipient h2 {
    max-width: 760px;
    margin: 9px auto 4px;
    overflow-wrap: anywhere;
    color: #132d4f;
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 39px;
    font-weight: 600;
    line-height: 1.12;
}

.certificate-name-line {
    width: 280px;
    height: 2px;
    margin: 0 auto 9px;
    background: #caa94d;
}

.certificate-description {
    margin: 0;
    color: #526175;
    font-size: 12px;
    line-height: 1.5;
}

.certificate-recipient h3 {
    margin: 7px 0 1px;
    color: #193e68;
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 22px;
    font-weight: 600;
}

.certificate-description-id {
    margin: 0;
    color: #8b7b58;
    font-size: 11px;
    font-style: italic;
}

.certificate-topics {
    margin: 11px 0 0;
    color: #7b8798;
    font-size: 10px;
    letter-spacing: 0.35px;
}

.certificate-details {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    align-items: end;
    gap: 24px;
    margin-top: auto;
    padding-top: 17px;
    border-top: 1px solid rgba(19, 45, 79, 0.16);
}

.certificate-signature,
.certificate-meta {
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 0;
    text-align: center;
}

.certificate-script {
    height: 40px;
    margin-bottom: 2px;
}

.certificate-signature-script {
    color: #132d4f !important;
    font-family: 'Brush Script MT', 'Segoe Script', cursive !important;
    font-size: 34px !important;
}

.certificate-signature-line {
    width: 180px;
    border-top: 2px solid #132d4f;
}

.certificate-signature strong {
    margin-top: 6px;
    color: #132d4f;
    font-size: 12px;
}

.certificate-signature span {
    margin-top: 3px;
    color: #788396;
    font-size: 9px;
}

.certificate-seal {
    display: grid;
    place-items: center;
}

.certificate-seal-ring {
    display: flex;
    width: 86px;
    height: 86px;
    box-sizing: border-box;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border: 2px solid #caa94d;
    border-radius: 50%;
    outline: 1px solid rgba(202, 169, 77, 0.55);
    outline-offset: -7px;
    color: #132d4f;
    background: radial-gradient(circle, #fffef6 0%, #f5edda 100%);
}

.certificate-seal-ring span {
    color: #a28234;
    font-size: 7px;
    font-weight: 800;
    letter-spacing: 1px;
}

.certificate-seal-ring strong {
    margin: 2px 0;
    font-size: 19px;
    letter-spacing: 2px;
}

.certificate-seal-ring small {
    color: #768094;
    font-size: 7px;
    letter-spacing: 1px;
}

.certificate-meta-label,
.certificate-id span {
    color: #8b7b58;
    font-size: 8px;
    font-weight: 700;
    letter-spacing: 1.5px;
}

.certificate-meta strong {
    margin-top: 5px;
    color: #193e68;
    font-size: 12px;
}

.certificate-meta small {
    margin-top: 2px;
    color: #788396;
    font-size: 9px;
}

.certificate-id {
    width: 100%;
    box-sizing: border-box;
    margin-top: 8px;
    padding: 6px 9px;
    border: 1px solid rgba(19, 45, 79, 0.15);
    border-radius: 5px;
    background: rgba(255, 255, 255, 0.55);
}

.certificate-id strong {
    display: block;
    margin-top: 3px;
    overflow-wrap: anywhere;
    color: #193e68;
    font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
    font-size: 9px;
}

.certificate-footer {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    margin-top: 14px;
    padding-top: 9px;
    border-top: 1px solid rgba(19, 45, 79, 0.1);
    color: #8b95a5;
    font-size: 8px;
    line-height: 1.4;
}

.certificate-footer span:last-child {
    text-align: right;
}

@media (max-width: 700px) {
    .certificate-preview {
        margin-right: -4px;
        margin-left: -4px;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}