/* ========================================
   MOBILE OPTIMIZATION - ENHANCED VERSION
   Cải thiện giao diện mobile gọn gàng hơn
   ======================================== */

/* ========================================
   NÚT SCROLL TO TOP - CẢI TIẾN
   Chỉ hiện khi cuộn xuống đủ xa (>500px)
   ======================================== */

.scroll-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 50px;
    height: 50px;
    background: var(--bg-gradient);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 998;
    opacity: 0;
    visibility: hidden;
    transform: translateY(100px) scale(0.5);
    pointer-events: none;
}

/* Chỉ hiện khi cuộn xu��ng > 500px */
.scroll-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0) scale(1);
    pointer-events: all;
}

.scroll-to-top:hover {
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.6);
}

.scroll-to-top:active {
    transform: translateY(-2px) scale(1.05);
}

.scroll-to-top i {
    animation: bounceUpDown 2s ease-in-out infinite;
}

@keyframes bounceUpDown {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-4px);
    }
}

/* Mobile: Nút nhỏ hơn và vị trí tối ưu */
@media (max-width: 767px) {
    .scroll-to-top {
        width: 46px;
        height: 46px;
        bottom: 16px;
        right: 16px;
        font-size: 18px;
        box-shadow: 0 3px 12px rgba(102, 126, 234, 0.4);
    }
    
    .scroll-to-top:hover {
        transform: translateY(-3px) scale(1.08);
    }
}

@media (max-width: 479px) {
    .scroll-to-top {
        width: 44px;
        height: 44px;
        bottom: 14px;
        right: 14px;
        font-size: 17px;
    }
}

/* ========================================
   MOBILE HEADER - COMPACT VERSION
   ======================================== */

@media (max-width: 767px) {
    .top-header {
        height: 56px;
        padding: 0 10px 0 60px;
        gap: 8px;
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    }
    
    .header-center {
        flex: 1;
        max-width: none;
    }
    
    .search-bar {
        padding: 8px 12px;
        font-size: 14px;
        border-radius: 10px;
    }
    
    .search-bar input {
        font-size: 14px;
    }
    
    .search-bar i {
        font-size: 14px;
    }
    
    .header-right {
        gap: 6px;
    }
    
    .btn-create-quiz,
    .theme-toggle-btn {
        width: 40px;
        height: 40px;
        padding: 0;
        border-radius: 10px;
        display: flex;
        align-items: center;
        justify-content: center;
    }
    
    .btn-create-quiz span {
        display: none;
    }
    
    .btn-create-quiz i,
    .theme-toggle-btn i {
        font-size: 16px;
        margin: 0;
    }
    
    .user-avatar-small {
        width: 34px;
        height: 34px;
        font-size: 13px;
    }
}

/* ========================================
   MOBILE CONTENT - COMPACT SPACING
   ======================================== */

@media (max-width: 767px) {
    .main-content-area {
        padding: 12px 10px;
    }
    
    .page-header {
        margin-bottom: 16px;
        padding: 0;
    }
    
    .page-title {
        font-size: 20px;
        gap: 8px;
        line-height: 1.3;
    }
    
    .page-title i {
        font-size: 20px;
    }
    
    /* Section spacing */
    .stats-section,
    .recent-section,
    .features-section {
        padding: 16px 12px;
        margin-bottom: 14px;
        border-radius: 14px;
    }
    
    .section-title {
        font-size: 17px;
        margin-bottom: 12px;
    }
    
    .section-header {
        margin-bottom: 12px;
        padding-bottom: 10px;
    }
}

/* ========================================
   MOBILE STATS - COMPACT CARDS
   ======================================== */

@media (max-width: 767px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    
    .stat-card {
        padding: 14px 12px;
        gap: 10px;
        border-radius: 12px;
    }
    
    .stat-icon {
        width: 40px;
        height: 40px;
        font-size: 18px;
        border-radius: 10px;
    }
    
    .stat-value {
        font-size: 20px;
        margin-bottom: 2px;
    }
    
    .stat-label {
        font-size: 11px;
        line-height: 1.2;
    }
}

@media (max-width: 479px) {
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 10px;
    }
    
    .stat-card {
        flex-direction: row;
        padding: 12px;
        gap: 12px;
    }
    
    .stat-icon {
        width: 44px;
        height: 44px;
        font-size: 20px;
    }
    
    .stat-content {
        flex: 1;
        text-align: left;
    }
    
    .stat-value {
        font-size: 22px;
    }
    
    .stat-label {
        font-size: 12px;
    }
}

/* ========================================
   MOBILE FORMS - COMPACT & CLEAN
   ======================================== */

@media (max-width: 767px) {
    .form-card {
        padding: 18px 14px;
        border-radius: 14px;
    }
    
    .form-group {
        margin-bottom: 16px;
    }
    
    .form-group label {
        font-size: 13px;
        margin-bottom: 6px;
        font-weight: 600;
    }
    
    .form-input,
    .form-select,
    .form-textarea {
        padding: 11px 14px;
        font-size: 15px;
        border-radius: 10px;
        border-width: 1.5px;
    }
    
    .form-textarea {
        min-height: 100px;
        line-height: 1.5;
    }
    
    .form-textarea.large {
        min-height: 140px;
    }
    
    .btn-paste-inline {
        padding: 9px 14px;
        font-size: 13px;
        margin-bottom: 8px;
        border-radius: 8px;
    }
    
    .form-actions {
        gap: 10px;
        margin-top: 18px;
    }
    
    .btn-primary,
    .btn-secondary {
        padding: 12px 20px;
        font-size: 14px;
        border-radius: 10px;
    }
}

/* ========================================
   MOBILE QUIZ CARDS - COMPACT
   ======================================== */

@media (max-width: 767px) {
    .quiz-grid {
        grid-template-columns: 1fr;
        gap: 12px;
    }
    
    .quiz-card,
    .quiz-item {
        padding: 14px;
        border-radius: 12px;
        border-width: 1.5px;
    }
    
    .quiz-card-header h3,
    .quiz-item-info h3 {
        font-size: 16px;
        margin-bottom: 6px;
        line-height: 1.3;
    }
    
    .quiz-card-header p,
    .quiz-item-info p {
        font-size: 13px;
        margin-bottom: 8px;
        line-height: 1.4;
    }
    
    .quiz-card-meta,
    .quiz-item-meta {
        font-size: 11px;
        gap: 8px;
        flex-wrap: wrap;
    }
    
    .quiz-card-meta span,
    .quiz-item-meta span {
        padding: 4px 10px;
        border-radius: 6px;
    }
    
    .quiz-card-actions,
    .quiz-item-actions {
        gap: 8px;
        margin-top: 10px;
    }
    
    .btn-sm {
        padding: 7px 12px;
        font-size: 12px;
        border-radius: 8px;
    }
}

/* ========================================
   MOBILE QUESTION CARDS - OPTIMIZED
   ======================================== */

@media (max-width: 767px) {
    .question-card,
    .question-card-modern {
        padding: 16px 12px;
        margin-bottom: 14px;
        border-radius: 12px;
        border-width: 1.5px;
    }
    
    .question-header {
        gap: 10px;
        margin-bottom: 12px;
    }
    
    .question-number {
        min-width: 34px;
        height: 34px;
        font-size: 14px;
        border-radius: 10px;
    }
    
    .question-text,
    .question-text-modern {
        font-size: 15px;
        line-height: 1.6;
        padding: 12px;
        border-radius: 10px;
    }
    
    .options,
    .options-modern {
        gap: 10px;
        margin-top: 12px;
    }
    
    .option,
    .option-modern {
        padding: 12px;
        gap: 10px;
        min-height: 50px;
        border-radius: 10px;
        border-width: 1.5px;
    }
    
    .option input[type="radio"],
    .option-modern input[type="radio"] {
        width: 20px;
        height: 20px;
    }
    
    .option-label,
    .option-modern .option-letter {
        min-width: 24px;
        font-size: 14px;
    }
    
    .option-text,
    .option-modern .option-text {
        font-size: 14px;
        line-height: 1.5;
    }
    
    /* Giảm hiệu ứng transform để mượt hơn */
    .option:hover,
    .option-modern:hover {
        transform: translateX(4px) scale(1.005);
    }
    
    .option.selected,
    .option-modern.selected {
        transform: translateX(6px) scale(1.01);
    }
}

/* ========================================
   MOBILE QUIZ NAVIGATION - COMPACT
   ======================================== */

@media (max-width: 767px) {
    .quiz-sidebar-right {
        padding: 14px;
        border-radius: 12px;
    }
    
    .grid-title {
        font-size: 14px;
        margin-bottom: 10px;
    }
    
    .question-grid {
        grid-template-columns: repeat(7, 1fr);
        gap: 6px;
    }
    
    .question-grid-item {
        font-size: 12px;
        min-height: 38px;
        border-radius: 8px;
        border-width: 1.5px;
        padding: 0;
    }
    
    .quiz-navigation {
        gap: 10px;
        margin-top: 14px;
    }
    
    .btn-nav {
        padding: 11px 18px;
        font-size: 13px;
        border-radius: 10px;
    }
}

@media (max-width: 479px) {
    .question-grid {
        grid-template-columns: repeat(6, 1fr);
        gap: 5px;
    }
    
    .question-grid-item {
        font-size: 11px;
        min-height: 36px;
    }
}

/* ========================================
   MOBILE RESULTS - COMPACT
   ======================================== */

@media (max-width: 767px) {
    .results-header {
        padding: 28px 18px;
        border-radius: 14px;
        margin-bottom: 16px;
    }
    
    .performance-badge {
        font-size: 50px;
        margin-bottom: 10px;
    }
    
    .quiz-title-result {
        font-size: 14px;
        margin-bottom: 14px;
    }
    
    .score-display {
        font-size: 54px;
        margin-bottom: 10px;
    }
    
    .score-text {
        font-size: 16px;
    }
    
    .results-stats {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
        margin-bottom: 16px;
    }
    
    .stat-card {
        padding: 16px 12px;
    }
    
    .stat-number {
        font-size: 24px;
    }
    
    .stat-label {
        font-size: 11px;
    }
    
    .action-buttons-container {
        padding: 14px;
        gap: 8px;
        margin: 16px 0;
        border-radius: 12px;
    }
    
    .action-buttons-container .btn {
        padding: 11px 16px;
        font-size: 13px;
        border-radius: 10px;
    }
    
    .result-question {
        padding: 14px;
        margin-bottom: 12px;
        border-radius: 12px;
    }
    
    .result-question-text {
        font-size: 14px;
        margin-bottom: 10px;
    }
    
    .result-options {
        gap: 8px;
    }
    
    .result-option {
        padding: 11px 12px;
        border-radius: 10px;
        border-width: 1.5px;
    }
    
    .result-option .option-text {
        font-size: 13px;
    }
}

@media (max-width: 479px) {
    .results-stats {
        grid-template-columns: 1fr;
    }
    
    .action-buttons-container {
        flex-direction: column;
    }
    
    .action-buttons-container .btn {
        width: 100%;
    }
}

/* ========================================
   MOBILE MODAL - FULL SCREEN ON SMALL
   ======================================== */

@media (max-width: 767px) {
    .modal-content {
        width: 95%;
        max-width: 500px;
        max-height: 90vh;
        border-radius: 14px;
    }
    
    .modal-header {
        padding: 16px;
    }
    
    .modal-header h3 {
        font-size: 17px;
    }
    
    .modal-close {
        width: 36px;
        height: 36px;
        font-size: 20px;
    }
    
    .modal-body {
        padding: 16px;
        max-height: calc(90vh - 130px);
    }
    
    .modal-footer {
        padding: 16px;
        gap: 10px;
    }
}

@media (max-width: 479px) {
    .modal-content {
        width: 100%;
        max-width: 100%;
        height: 100vh;
        max-height: 100vh;
        border-radius: 0;
    }
    
    .modal-body {
        max-height: calc(100vh - 130px);
    }
}

/* ========================================
   MOBILE AI SECTION - COMPACT
   ======================================== */

@media (max-width: 767px) {
    .ai-info-banner {
        padding: 12px;
        font-size: 13px;
        gap: 10px;
        border-radius: 10px;
    }
    
    .ai-info-banner i {
        font-size: 18px;
    }
    
    .file-upload-area {
        padding: 18px 14px;
        border-radius: 12px;
    }
    
    .file-upload-content h4 {
        font-size: 14px;
        margin-bottom: 6px;
    }
    
    .file-upload-content p {
        font-size: 12px;
        margin-bottom: 10px;
    }
    
    .divider-with-text {
        margin: 16px 0;
        font-size: 12px;
    }
    
    .ai-preview-section {
        padding: 16px 12px;
        border-radius: 12px;
    }
    
    .ai-preview-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
        margin-bottom: 14px;
    }
    
    .ai-preview-header h3 {
        font-size: 17px;
    }
    
    .preview-question {
        padding: 14px;
        margin-bottom: 12px;
        border-radius: 12px;
    }
    
    .preview-question-number {
        min-width: 34px;
        height: 34px;
        font-size: 14px;
    }
    
    .preview-question-text {
        font-size: 14px;
        line-height: 1.5;
    }
    
    .preview-options {
        gap: 8px;
    }
    
    .preview-option {
        padding: 11px 12px;
        border-radius: 10px;
        border-width: 1.5px;
    }
    
    .preview-option-text {
        font-size: 13px;
    }
    
    .preview-correct-answer {
        padding: 6px 12px;
        font-size: 11px;
        border-radius: 12px;
    }
}

/* ========================================
   MOBILE TOAST - BOTTOM CENTER
   ======================================== */

@media (max-width: 767px) {
    .toast {
        bottom: 14px;
        right: 14px;
        left: 14px;
        min-width: auto;
        padding: 12px 14px;
        font-size: 13px;
        border-radius: 10px;
    }
    
    .toast i {
        font-size: 18px;
    }
}

/* ========================================
   PERFORMANCE OPTIMIZATIONS
   ======================================== */

@media (max-width: 767px) {
    /* Giảm animations phức tạp trên mobile */
    .option::before,
    .option::after,
    .option-modern::before,
    .option-modern::after {
        display: none;
    }
    
    /* Đơn giản hóa transitions */
    .option,
    .option-modern,
    .question-card,
    .question-card-modern,
    .btn {
        transition: all 0.2s ease;
    }
    
    /* Tắt hover effects trên touch devices */
    @media (hover: none) {
        .option:hover,
        .option-modern:hover {
            transform: none;
            border-color: var(--border-color);
        }
        
        .btn:hover {
            transform: none;
        }
    }
}

/* ========================================
   LANDSCAPE MODE - OPTIMIZED
   ======================================== */

@media (max-height: 500px) and (orientation: landscape) {
    .top-header {
        height: 48px;
    }
    
    .mobile-menu-toggle {
        width: 38px;
        height: 38px;
    }
    
    .question-card,
    .question-card-modern {
        padding: 12px;
    }
    
    .question-text,
    .question-text-modern {
        padding: 10px;
        font-size: 14px;
    }
    
    .option,
    .option-modern {
        padding: 10px;
        min-height: 44px;
    }
    
    .results-header {
        padding: 16px;
    }
    
    .performance-badge {
        font-size: 36px;
        margin-bottom: 6px;
    }
    
    .score-display {
        font-size: 40px;
        margin-bottom: 6px;
    }
    
    .results-stats {
        grid-template-columns: repeat(4, 1fr);
        gap: 8px;
    }
}

/* ========================================
   VERY SMALL SCREENS - ULTRA COMPACT
   ======================================== */

@media (max-width: 359px) {
    .top-header {
        padding: 0 6px 0 54px;
    }
    
    .mobile-menu-toggle {
        width: 38px;
        height: 38px;
        left: 10px;
        top: 10px;
    }
    
    .btn-create-quiz,
    .theme-toggle-btn {
        width: 36px;
        height: 36px;
    }
    
    .page-title {
        font-size: 18px;
    }
    
    .section-title {
        font-size: 16px;
    }
    
    .form-card {
        padding: 14px 10px;
    }
    
    .question-card,
    .question-card-modern {
        padding: 12px 10px;
    }
    
    .option,
    .option-modern {
        padding: 10px;
    }
    
    .question-grid {
        grid-template-columns: repeat(5, 1fr);
    }
}

/* ========================================
   SAFE AREA INSETS - NOTCHED DEVICES
   ======================================== */

@supports (padding: max(0px)) {
    @media (max-width: 767px) {
        .top-header {
            padding-left: max(60px, calc(env(safe-area-inset-left) + 60px));
            padding-right: max(10px, calc(env(safe-area-inset-right) + 10px));
            padding-top: env(safe-area-inset-top);
        }
        
        .mobile-menu-toggle {
            left: max(12px, calc(env(safe-area-inset-left) + 12px));
            top: max(12px, calc(env(safe-area-inset-top) + 12px));
        }
        
        .main-content-area {
            padding-left: max(10px, calc(env(safe-area-inset-left) + 10px));
            padding-right: max(10px, calc(env(safe-area-inset-right) + 10px));
            padding-bottom: max(12px, calc(env(safe-area-inset-bottom) + 12px));
        }
        
        .scroll-to-top {
            bottom: max(14px, calc(env(safe-area-inset-bottom) + 14px));
            right: max(14px, calc(env(safe-area-inset-right) + 14px));
        }
        
        .toast {
            bottom: max(14px, calc(env(safe-area-inset-bottom) + 14px));
            left: max(14px, calc(env(safe-area-inset-left) + 14px));
            right: max(14px, calc(env(safe-area-inset-right) + 14px));
        }
    }
}

/* ========================================
   ACCESSIBILITY IMPROVEMENTS
   ======================================== */

@media (max-width: 767px) {
    /* Larger touch targets */
    button,
    a,
    .nav-item,
    input[type="radio"],
    input[type="checkbox"] {
        min-height: 44px;
    }
    
    /* Better focus indicators */
    *:focus-visible {
        outline: 2px solid var(--primary-color);
        outline-offset: 2px;
    }
    
    /* Prevent text selection on buttons */
    button,
    .btn {
        -webkit-user-select: none;
        user-select: none;
    }
}

/* ========================================
   DARK MODE ADJUSTMENTS FOR MOBILE
   ======================================== */

@media (max-width: 767px) {
    body.dark-mode .question-card,
    body.dark-mode .question-card-modern,
    body.dark-mode .option,
    body.dark-mode .option-modern {
        border-color: rgba(255, 255, 255, 0.1);
    }
    
    body.dark-mode .option:hover,
    body.dark-mode .option-modern:hover {
        border-color: rgba(255, 255, 255, 0.2);
    }
    
    body.dark-mode .option.selected,
    body.dark-mode .option-modern.selected {
        border-color: var(--primary-color);
        background: rgba(102, 126, 234, 0.15);
    }
}