/* ===================== QUIZ MODERN DESIGN - 2025 ===================== */

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    --bg-light: #f8fafc;
    --bg-white: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --quiz-question-font-size: 22px;
    --quiz-answer-font-size: 16px;
}

/* ===================== CONTAINER ===================== */
.quiz-container-modern {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
    background: var(--bg-light);
    min-height: 100vh;
}

/* ===================== HEADER ===================== */
.quiz-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, #3b82f6 100%);
    border-radius: var(--radius-lg);
    padding: 24px 32px;
    margin-top: 24px;
    margin-bottom: 24px;
    box-shadow: var(--shadow-lg);
    color: white;
}

.quiz-header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 24px;
}

.quiz-stats {
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 16px;
    font-weight: 500;
    background: rgba(255, 255, 255, 0.2);
    padding: 8px 16px;
    border-radius: var(--radius-md);
    backdrop-filter: blur(10px);
}

.stat-item i {
    font-size: 18px;
}

/* ===================== PROGRESS TABLE ===================== */
.progress-table-wrapper {
    margin-top: 20px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    padding: 16px;
    backdrop-filter: blur(10px);
}

.progress-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13px;
}

.progress-table thead th {
    text-align: left;
    padding: 8px 12px;
    font-weight: 600;
    color: rgba(255, 255, 255, 0.9);
    border-bottom: 2px solid rgba(255, 255, 255, 0.2);
}

.progress-table tbody tr {
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    transition: background 0.2s ease;
}

.progress-table tbody tr:hover {
    background: rgba(255, 255, 255, 0.1);
}

.progress-table tbody tr:last-child {
    border-bottom: none;
}

.progress-table td {
    padding: 10px 12px;
    color: rgba(255, 255, 255, 0.95);
}

.progress-table td:first-child {
    font-weight: 500;
    min-width: 140px;
}

.progress-table td:first-child i {
    margin-right: 8px;
    width: 18px;
    text-align: center;
    color: rgba(255, 255, 255, 0.8);
}

.progress-table td:nth-child(2) {
    width: 50%;
    min-width: 200px;
}

.progress-table td:last-child {
    text-align: right;
    font-weight: 600;
    min-width: 60px;
}

.progress-bar-wrapper {
    position: relative;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 20px;
    height: 24px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, #10b981 0%, #059669 100%);
    border-radius: 20px;
    transition: width 0.3s ease;
    position: relative;
}

.progress-bar-danger {
    background: linear-gradient(90deg, #ef4444 0%, #dc2626 100%);
}

.progress-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 11px;
    font-weight: 600;
    color: white;
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    z-index: 1;
    white-space: nowrap;
}

.progress-count {
    color: rgba(255, 255, 255, 0.95);
    font-size: 14px;
}

/* ===================== MAIN WRAPPER ===================== */
.quiz-main-wrapper {
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 24px;
    align-items: start;
}

/* ===================== SIDEBAR ===================== */
.quiz-sidebar {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: 20px;
    box-shadow: var(--shadow-md);
    height: fit-content;
    position: sticky;
    top: 20px;
    max-height: calc(100vh - 40px);
    overflow-y: auto;
    align-self: start;
}

.sidebar-section {
    margin-bottom: 24px;
}

.sidebar-section:last-child {
    margin-bottom: 0;
}

.sidebar-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.sidebar-title i {
    color: var(--primary-color);
}

.sidebar-header-actions {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

/* ===================== CATEGORY SELECT ===================== */
.category-select-modern {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    background: var(--bg-white);
    color: var(--text-primary);
    cursor: pointer;
    transition: var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23334155' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 40px;
}

.category-select-modern:hover {
    border-color: var(--primary-color);
}

.category-select-modern:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* ===================== SEARCH OVERLAY ===================== */
.sidebar-search-wrapper {
    position: relative;
    margin-bottom: 24px;
}

.sidebar-search-wrapper .search-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.sidebar-search-wrapper .sidebar-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0;
    display: flex;
    align-items: center;
    gap: 8px;
}

.sidebar-search-wrapper .sidebar-title i {
    color: var(--primary-color);
}

.search-wrapper {
    position: relative;
}

.search-input-modern {
    width: 100%;
    padding: 12px 16px 12px 44px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 14px;
    transition: var(--transition);
    background: var(--bg-white);
}

.search-input-modern:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.search-icon {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    pointer-events: none;
}

/* Kết quả tìm kiếm dạng overlay - hiện đè lên danh sách câu hỏi */
.search-results-overlay {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    min-width: 280px;
    z-index: 100;
    max-height: 380px;
    overflow-y: auto;
    border-radius: var(--radius-md);
    background: var(--bg-white);
    border: 2px solid var(--primary-color);
    box-shadow: var(--shadow-xl);
    display: none;
}

.search-results-overlay.show {
    display: block;
}

.search-results-overlay .search-results-header {
    padding: 10px 16px;
    background: var(--primary-color);
    color: white;
    font-size: 13px;
    font-weight: 600;
    border-radius: calc(var(--radius-md) - 2px) calc(var(--radius-md) - 2px) 0 0;
    display: flex;
    align-items: center;
    gap: 8px;
    position: sticky;
    top: 0;
    z-index: 1;
}

.search-results-overlay .search-result-item {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    padding: 12px 16px;
    cursor: pointer;
    border-bottom: 1px solid var(--border-color);
    transition: background 0.2s ease;
}

.search-results-overlay .search-result-item:last-of-type {
    border-bottom: none;
}

.search-results-overlay .search-result-item:hover {
    background: #eff6ff;
}

.search-results-overlay .search-result-badge {
    flex-shrink: 0;
    background: var(--primary-color);
    color: white;
    font-size: 12px;
    font-weight: 600;
    padding: 4px 8px;
    border-radius: 6px;
    min-width: 52px;
    text-align: center;
}

.search-results-overlay .search-result-content {
    flex: 1;
    min-width: 0;
    font-size: 13px;
    line-height: 1.5;
    color: var(--text-primary);
    word-wrap: break-word;
    word-break: break-word;
    overflow-wrap: break-word;
}

.search-results-overlay .search-result-content strong {
    color: var(--primary-color);
    font-weight: 600;
    background: rgba(37, 99, 235, 0.12);
    padding: 0 2px;
}

.search-results-overlay .search-result-item:hover .search-result-badge {
    background: var(--primary-hover);
}

.search-results-overlay .search-result-item:hover .search-result-content {
    color: var(--text-primary);
}

.search-results-overlay .search-result-item:hover .search-result-content strong {
    color: white;
    background: rgba(255, 255, 255, 0.3);
}

.search-results-overlay .search-result-more {
    padding: 12px 16px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 12px;
    font-style: italic;
    border-top: 1px dashed var(--border-color);
}

.search-results-overlay .search-loading {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    padding: 24px;
}

.search-results-overlay .search-no-results {
    padding: 24px 16px;
    text-align: center;
    color: var(--text-secondary);
    font-size: 14px;
}

.search-results-overlay .search-no-results i {
    display: block;
    margin-bottom: 8px;
    opacity: 0.6;
}

/* ===================== QUESTION NUMBERS GRID ===================== */
.question-numbers-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 8px;
    max-height: 400px;
    overflow-y: auto;
    padding: 4px;
}

.question-number-huy {
    width: 100%;
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--bg-white);
    color: var(--text-primary);
    font-weight: 600;
    font-size: 14px;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}

.question-number-huy:hover {
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.question-number-huy.active-huy {
    background: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
    border-color: #f59e0b;
    color: white;
    box-shadow: var(--shadow-md);
}

.question-number-huy.correct-huy {
    background: linear-gradient(135deg, var(--success-color) 0%, #059669 100%);
    border-color: var(--success-color);
    color: white;
}

.question-number-huy.incorrect-huy {
    background: linear-gradient(135deg, var(--error-color) 0%, #dc2626 100%);
    border-color: var(--error-color);
    color: white;
}

/* ===================== BUTTONS ===================== */
.btn-reset-scores {
    background: var(--error-color);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    padding: 4px 8px;
    cursor: pointer;
    transition: var(--transition);
    font-size: 12px;
}

.btn-reset-scores:hover {
    background: #dc2626;
    transform: scale(1.05);
}

.btn-thi-thu {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, var(--primary-color) 0%, #3b82f6 100%);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    box-shadow: var(--shadow-md);
}

.btn-thi-thu:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-thi-thu-mobile {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, var(--primary-color) 0%, #3b82f6 100%);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-top: 20px;
}

/* ===================== QUIZ CONTENT ===================== */
.quiz-content {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: 32px;
    box-shadow: var(--shadow-md);
}

/* ===================== NAVIGATION ===================== */
.quiz-navigation-top,
.quiz-navigation-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 8px;
    margin-bottom: 12px;
    padding: 0;
    background: var(--bg-light);
    border-radius: var(--radius-md);
}

.quiz-navigation-bottom {
    margin-top: 12px;
    margin-bottom: 0;
}

.btn-nav {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 6px 12px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.btn-nav:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-nav:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-nav i {
    font-size: 12px;
}

.btn-prev {
    background: var(--text-secondary);
}

.btn-prev:hover:not(:disabled) {
    background: #475569;
}

.nav-info {
    flex: 1;
    text-align: center;
}

.question-counter {
    display: block;
    font-size: 14px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.keyboard-hint {
    font-size: 10px;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 4px;
}

.nav-actions {
    flex: 1;
    display: flex;
    justify-content: center;
}

.btn-action {
    padding: 10px 20px;
    background: var(--warning-color);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 8px;
}

.btn-action:hover {
    background: #d97706;
    transform: translateY(-2px);
}

/* ===================== QUESTION CARD ===================== */
.question-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: 15px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.question-header {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
    flex-wrap: wrap;
}

.question-badge {
    background: linear-gradient(135deg, var(--primary-color) 0%, #3b82f6 100%);
    color: white;
    padding: 8px 16px;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 14px;
}

.category-badge {
    background: var(--bg-light);
    color: var(--text-primary);
    padding: 8px 16px;
    border-radius: var(--radius-md);
    font-weight: 500;
    font-size: 14px;
    border: 1px solid var(--border-color);
}

.badge-diem-liet {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    color: white;
    border-color: #dc2626;
    font-weight: 600;
    box-shadow: 0 2px 4px rgba(239, 68, 68, 0.3);
}

.question-text {
    font-size: var(--quiz-question-font-size);
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.7;
    margin-bottom: 24px;
    letter-spacing: 0.3px;
}

.question-text * {
    font-size: inherit;
    font-weight: inherit;
    color: inherit;
    line-height: inherit;
    letter-spacing: inherit;
}

.question-text h3,
.question-text h5 {
    margin: 0;
    color: var(--text-primary);
}

.question-image-wrapper {
    margin: 24px 0;
    text-align: center;
}

.question-image-huy {
    max-width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
}

/* ===================== ANSWERS ===================== */
.answers-container {
    margin-top: 24px;
    font-size: var(--quiz-answer-font-size);
}

.answer-huy {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 16px 20px;
    margin-bottom: 12px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-white);
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    font-size: inherit;
}

.answer-huy:hover {
    border-color: var(--primary-color);
    background: #f0f7ff;
    transform: translateX(4px);
    box-shadow: var(--shadow-sm);
}

.answer-huy input[type="radio"] {
    display: none;
}

.answer-number-huy {
    font-weight: 600;
    font-size: 16px;
    color: var(--primary-color);
    min-width: 24px;
    flex-shrink: 0;
}

.answer-huy.correct-huy {
    background: linear-gradient(135deg, #d1fae5 0%, #a7f3d0 100%);
    border-color: var(--success-color);
    color: var(--text-primary);
}

.answer-huy.incorrect-huy {
    background: linear-gradient(135deg, #fee2e2 0%, #fecaca 100%);
    border-color: var(--error-color);
    color: var(--text-primary);
}

.answer-huy.correct-huy .answer-number-huy,
.answer-huy.incorrect-huy .answer-number-huy {
    font-size: 18px;
}

/* ===================== EXPLANATION ===================== */
.explanation-box {
    margin-top: 24px;
    padding: 20px;
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    border-left: 4px solid var(--warning-color);
    border-radius: var(--radius-md);
    animation: slideDown 0.3s ease-out;
}

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

.explanation-header {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 600;
    font-size: 16px;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.explanation-header i {
    color: var(--warning-color);
    font-size: 20px;
}

.explanation-content {
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 15px;
}

.explanation-text {
    margin: 0;
    padding: 16px;
    background: rgba(255, 255, 255, 0.7);
    border-radius: var(--radius-sm);
}

/* ===================== LOADING ===================== */
.quiz-loading-modern {
    text-align: center;
    padding: 40px 20px;
}

.loading-spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 16px;
}

.loading-spinner-small {
    width: 24px;
    height: 24px;
    border: 2px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 8px;
}

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

.quiz-loading-modern p {
    color: var(--text-secondary);
    font-size: 16px;
    margin: 8px 0;
}

.loading-hint {
    font-size: 14px;
    color: var(--text-secondary);
    font-style: italic;
}

.question-loading {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    z-index: 10;
    background: rgba(255, 255, 255, 0.95);
    padding: 20px;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
}

.question-loading p {
    color: var(--text-secondary);
    font-size: 14px;
    margin: 8px 0 0 0;
}

#quizContent {
    position: relative;
    transition: opacity 0.2s ease;
}

/* ===================== MODAL ===================== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1050;
    overflow: hidden;
    outline: 0;
}

.modal.show {
    display: block;
}

.modal.fade {
    opacity: 0;
    transition: opacity 0.15s linear;
}

.modal.fade.show {
    opacity: 1;
}

.modal-dialog {
    position: relative;
    width: auto;
    max-width: 500px;
    margin: 1.75rem auto;
    pointer-events: none;
}

.modal-dialog-centered {
    display: flex;
    align-items: center;
    min-height: calc(100% - 3.5rem);
}

.modal-dialog-centered::before {
    display: block;
    height: calc(100vh - 3.5rem);
    content: "";
}

.modal-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1040;
}

.modal-backdrop.fade {
    opacity: 0;
}

.modal-backdrop.show {
    opacity: 1;
}

.modal-content-modern {
    position: relative;
    display: flex;
    flex-direction: column;
    width: 100%;
    pointer-events: auto;
    background-color: var(--bg-white);
    background-clip: padding-box;
    border-radius: var(--radius-lg);
    border: none;
    box-shadow: var(--shadow-xl);
    outline: 0;
}

.modal-header-modern {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px;
    border-bottom: 1px solid var(--border-color);
}

.modal-title-modern {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0;
}

.modal-title-modern i {
    color: var(--warning-color);
}

.btn-close-modal {
    background: none;
    border: none;
    font-size: 24px;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.btn-close-modal:hover {
    background: var(--bg-light);
    color: var(--text-primary);
}

.modal-body-modern {
    padding: 24px;
    font-size: 16px;
    color: var(--text-primary);
    line-height: 1.6;
}

.modal-footer-modern {
    display: flex;
    justify-content: flex-end;
    gap: 12px;
    padding: 24px;
    border-top: 1px solid var(--border-color);
}

.btn-modal {
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-md);
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.btn-cancel {
    background: var(--bg-light);
    color: var(--text-primary);
}

.btn-cancel:hover {
    background: var(--border-color);
}

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

.btn-confirm:hover {
    background: #dc2626;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* ===================== MOBILE ACTIONS ===================== */
.quiz-mobile-actions {
    display: none;
    margin-top: 24px;
}

/* ===================== RESPONSIVE ===================== */
@media (max-width: 1024px) {
    .quiz-main-wrapper {
        grid-template-columns: 280px 1fr;
    }
}

@media (max-width: 768px) {
    :root {
        --quiz-question-font-size: 18px;
        --quiz-answer-font-size: 15px;
    }
    .quiz-container-modern {
        padding: 8px;
    }

    /* ===================== HEADER MOBILE ===================== */
    .quiz-header {
        padding: 16px;
        margin-top: 12px;
        margin-bottom: 12px;
        border-radius: var(--radius-md);
    }

    .quiz-header-content {
        flex-direction: column;
        align-items: center;
        gap: 16px;
    }

    .progress-table-wrapper {
        margin-top: 16px;
        padding: 12px;
    }

    .progress-table {
        font-size: 11px;
    }

    .progress-table thead th {
        padding: 6px 8px;
        font-size: 11px;
    }

    .progress-table td {
        padding: 8px;
    }

    .progress-table td:first-child {
        min-width: 100px;
        font-size: 11px;
    }

    .progress-table td:first-child i {
        margin-right: 4px;
        font-size: 12px;
    }

    .progress-table td:nth-child(2) {
        min-width: 150px;
    }

    .progress-bar-wrapper {
        height: 20px;
    }

    .progress-text {
        font-size: 10px;
    }

    .progress-count {
        font-size: 12px;
    }

    .quiz-stats {
        gap: 8px;
        width: 100%;
        justify-content: center;
        flex-wrap: wrap;
    }

    .stat-item {
        font-size: 12px;
        padding: 6px 10px;
        flex: 1;
        min-width: calc(33.333% - 6px);
        justify-content: center;
    }

    .stat-item i {
        font-size: 14px;
    }

    /* ===================== MAIN WRAPPER MOBILE ===================== */
    .quiz-main-wrapper {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    /* ===================== SIDEBAR MOBILE ===================== */
    .quiz-sidebar {
        position: static;
        max-height: none;
        order: 2;
        padding: 16px;
        border-radius: var(--radius-md);
    }

    .sidebar-section {
        margin-bottom: 16px;
    }

    .sidebar-title {
        font-size: 14px;
        margin-bottom: 8px;
    }

    .category-select-modern {
        padding: 10px 12px;
        font-size: 13px;
    }

    .search-input-modern {
        padding: 10px 12px 10px 40px;
        font-size: 13px;
    }

    .search-icon {
        left: 12px;
        font-size: 14px;
    }

    .question-numbers-grid {
        grid-template-columns: repeat(5, 1fr);
        gap: 6px;
        max-height: 300px;
        padding: 4px;
    }

    .question-number-huy {
        font-size: 13px;
        padding: 8px 4px;
    }

    .btn-reset-scores {
        padding: 4px 8px;
        font-size: 11px;
    }

    .btn-thi-thu {
        padding: 12px;
        font-size: 14px;
    }

    /* ===================== CONTENT MOBILE ===================== */
    .quiz-content {
        order: 1;
        padding: 16px;
        border-radius: var(--radius-md);
    }

    /* ===================== NAVIGATION MOBILE ===================== */
    .quiz-navigation-top,
    .quiz-navigation-bottom {
        flex-direction: row;
        gap: 8px;
        padding: 12px;
        margin-bottom: 16px;
    }

    .quiz-navigation-bottom {
        margin-top: 16px;
        margin-bottom: 0;
    }

    .btn-nav {
        flex: 1;
        padding: 10px 16px;
        font-size: 14px;
        min-width: 0;
    }

    .btn-nav span {
        display: none;
    }

    .btn-nav i {
        margin: 0;
    }

    .nav-info {
        display: none;
    }

    .nav-actions {
        display: none;
    }

    /* Navigation buttons chỉ hiển thị icon trên mobile */
    .quiz-navigation-top,
    .quiz-navigation-bottom {
        position: relative;
    }

    /* Tối ưu touch targets cho mobile */
    .btn-nav,
    .answer-huy,
    .question-number-huy {
        min-height: 44px;
        touch-action: manipulation;
    }

    /* Giảm margin/padding không cần thiết */
    .question-image-wrapper {
        margin: 12px 0;
    }

    /* Tối ưu modal trên mobile */
    .modal-content-modern {
        margin: 10px;
    }

    .modal-header-modern,
    .modal-body-modern,
    .modal-footer-modern {
        padding: 16px;
    }

    /* ===================== QUESTION CARD MOBILE ===================== */
    .question-card {
        padding: 16px;
        border-radius: var(--radius-md);
    }

    .question-header {
        margin-bottom: 16px;
        gap: 8px;
    }

    .question-badge,
    .category-badge {
        padding: 6px 12px;
        font-size: 12px;
    }

    .question-text {
        line-height: 1.6;
        margin-bottom: 16px;
        letter-spacing: 0.2px;
    }

    .question-text h3,
    .question-text h5 {
        font-size: var(--quiz-question-font-size);
    }

    .question-image-wrapper {
        margin: 16px 0;
    }

    .answers-container {
        margin-top: 16px;
    }

    .answer-huy {
        padding: 12px 14px;
        margin-bottom: 10px;
        border-radius: var(--radius-sm);
    }

    .answer-number-huy {
        font-size: 14px;
        min-width: 20px;
    }

    .explanation-box {
        margin-top: 16px;
        padding: 16px;
    }

    .explanation-header {
        font-size: 14px;
        margin-bottom: 10px;
    }

    .explanation-content {
        font-size: 14px;
    }

    /* ===================== MOBILE ACTIONS ===================== */
    .quiz-mobile-actions {
        display: block;
        margin-top: 16px;
    }

    .btn-thi-thu-mobile {
        padding: 12px;
        font-size: 14px;
    }
}

@media (max-width: 480px) {
    :root {
        --quiz-question-font-size: 17px;
        --quiz-answer-font-size: 14px;
    }
    .quiz-container-modern {
        padding: 6px;
    }

    .quiz-header {
        padding: 12px;
        margin-top: 12px;
        margin-bottom: 12px;
    }

    .quiz-header-content {
        gap: 12px;
    }

    .quiz-stats {
        gap: 6px;
    }

    .stat-item {
        font-size: 11px;
        padding: 5px 8px;
        min-width: calc(33.333% - 4px);
    }

    .stat-item i {
        font-size: 12px;
    }

    .quiz-sidebar {
        padding: 12px;
    }

    .sidebar-section {
        margin-bottom: 12px;
    }

    .sidebar-title {
        font-size: 13px;
    }

    .category-select-modern {
        padding: 8px 10px;
        font-size: 12px;
    }

    .search-input-modern {
        padding: 8px 10px 8px 36px;
        font-size: 12px;
    }

    .question-numbers-grid {
        grid-template-columns: repeat(4, 1fr);
        gap: 5px;
        max-height: 250px;
    }

    .question-number-huy {
        font-size: 11px;
        padding: 6px 2px;
    }

    .quiz-content {
        padding: 12px;
    }

    .quiz-navigation-top,
    .quiz-navigation-bottom {
        padding: 10px;
        gap: 6px;
    }

    .btn-nav {
        padding: 8px 12px;
        font-size: 13px;
    }

    .question-card {
        padding: 12px;
    }

    .question-header {
        margin-bottom: 12px;
    }

    .question-badge,
    .category-badge {
        padding: 5px 10px;
        font-size: 11px;
    }

    .question-text {
        line-height: 1.6;
        margin-bottom: 12px;
        letter-spacing: 0.2px;
    }

    .question-text h3,
    .question-text h5 {
        font-size: var(--quiz-question-font-size);
    }

    .answer-huy {
        padding: 10px 12px;
        margin-bottom: 8px;
    }

    .answer-number-huy {
        font-size: 13px;
        min-width: 18px;
    }

    .explanation-box {
        margin-top: 12px;
        padding: 12px;
    }

    .explanation-header {
        font-size: 13px;
    }

    .explanation-content {
        font-size: 13px;
    }

    .btn-thi-thu,
    .btn-thi-thu-mobile {
        padding: 10px;
        font-size: 13px;
        min-height: 44px;
    }

    /* Tối ưu touch targets cho mobile nhỏ */
    .btn-nav,
    .answer-huy,
    .question-number-huy,
    .btn-thi-thu,
    .btn-thi-thu-mobile {
        min-height: 44px;
        touch-action: manipulation;
    }

    /* Tối ưu modal trên mobile nhỏ */
    .modal-content-modern {
        margin: 5px;
    }

    .modal-header-modern,
    .modal-body-modern,
    .modal-footer-modern {
        padding: 12px;
    }

    .modal-title-modern {
        font-size: 16px;
    }

    .btn-modal {
        padding: 10px 16px;
        font-size: 14px;
        min-height: 44px;
    }
}

/* ===================== SCROLLBAR STYLING ===================== */
.question-numbers-grid::-webkit-scrollbar,
.quiz-sidebar::-webkit-scrollbar,
.search-results-modern::-webkit-scrollbar {
    width: 8px;
}

.question-numbers-grid::-webkit-scrollbar-track,
.quiz-sidebar::-webkit-scrollbar-track,
.search-results-modern::-webkit-scrollbar-track {
    background: var(--bg-light);
    border-radius: 4px;
}

.question-numbers-grid::-webkit-scrollbar-thumb,
.quiz-sidebar::-webkit-scrollbar-thumb,
.search-results-modern::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

.question-numbers-grid::-webkit-scrollbar-thumb:hover,
.quiz-sidebar::-webkit-scrollbar-thumb:hover,
.search-results-modern::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}