/**
 * PUMKIN.DEV Academic Design System - Responsive Stylesheet
 * Layer: 5 - Responsive (Media Queries 860px/480px, 2-Tier Nav, Gamification, Boss Lock, Sliders, Performance)
 */

/* Tablet & Mobile Harmonization (<= 860px) */
@media (max-width: 860px) {
    html, body {
        max-width: 100vw !important;
        overflow-x: hidden !important;
    }

    .wrapper {
        padding: 24px 16px !important;
        margin-top: 14px !important;
        max-width: 100% !important;
        box-sizing: border-box !important;
    }

    /* TOP NAVIGATION RESTRUCTURING: 2-TIER CLEAN MOBILE LAYOUT */
    .pumkin-nav-container {
        padding: 0 12px !important;
        margin: 0 0 12px 0 !important;
        position: sticky !important;
        top: 0 !important;
        z-index: 1000 !important;
    }

    .pumkin-nav {
        display: flex !important;
        flex-direction: row !important;
        flex-wrap: wrap !important;
        height: auto !important;
        min-height: auto !important;
        padding: 8px 0 6px 0 !important;
        row-gap: 8px !important;
        column-gap: 8px !important;
        align-items: center !important;
        justify-content: space-between !important;
    }

    /* TIER 1 (TOP ROW): BRAND LOGO ON LEFT, THEME & AUTH ON RIGHT */
    .brand-logo {
        order: 1 !important;
        flex: 1 1 auto !important;
        display: flex !important;
        align-items: center !important;
        gap: 8px !important;
        cursor: pointer !important;
    }

    .brand-logo span:first-child {
        font-size: 16px !important;
        font-weight: 800 !important;
        letter-spacing: 0.3px !important;
        white-space: nowrap !important;
    }

    .brand-badge {
        font-size: 9px !important;
        padding: 2px 6px !important;
        border-radius: 5px !important;
        display: inline-block !important;
    }

    .nav-right-actions {
        order: 2 !important;
        display: flex !important;
        align-items: center !important;
        gap: 6px !important;
        flex-shrink: 0 !important;
    }

    .btn-theme-toggle {
        width: 34px !important;
        height: 34px !important;
        font-size: 14px !important;
        border-radius: 8px !important;
        display: inline-flex !important;
        align-items: center !important;
        justify-content: center !important;
    }

    .btn-nav-auth {
        height: 34px !important;
        padding: 6px 11px !important;
        font-size: 12px !important;
        border-radius: 8px !important;
        display: inline-flex !important;
        align-items: center !important;
        gap: 5px !important;
        white-space: nowrap !important;
    }

    #nav-user-label {
        display: inline !important;
    }

    /* TIER 2 (BOTTOM ROW): 100% FULL-WIDTH NATIVE TOUCH SLIDER */
    .nav-scroll-wrapper {
        order: 3 !important;
        width: 100% !important;
        flex: 0 0 100% !important;
        margin: 2px 0 0 0 !important;
        padding: 0 !important;
        overflow: hidden !important;
        position: relative !important;
    }

    /* TRIỆT TIÊU 2 NÚT MŨI TÊN KÉO ĐẦU CUỐI GÂY VƯỚNG TRÊN MOBILE */
    .nav-scroll-arrow,
    .nav-scroll-prev,
    .nav-scroll-next {
        display: none !important;
    }

    .nav-links {
        width: 100% !important;
        flex: 1 1 100% !important;
        display: flex !important;
        gap: 6px !important;
        padding: 2px 2px 6px 2px !important;
        overflow-x: auto !important;
        overflow-y: hidden !important;
        -webkit-overflow-scrolling: touch !important;
        scroll-behavior: smooth !important;
        scrollbar-width: none !important; /* Firefox */
        -ms-overflow-style: none !important; /* IE/Edge */
    }

    .nav-links::-webkit-scrollbar {
        display: none !important; /* Chrome / Safari */
    }

    .nav-tab {
        padding: 7px 13px !important;
        font-size: 13px !important;
        font-weight: 600 !important;
        white-space: nowrap !important;
        border-radius: 8px !important;
        flex-shrink: 0 !important;
        line-height: 1.35 !important;
    }

    /* MOBILE TABLES & HORIZONTAL SCROLL ISOLATION */
    .table-responsive {
        margin: 14px 0 !important;
        border-radius: 8px !important;
        width: 100% !important;
        max-width: 100% !important;
        box-sizing: border-box !important;
    }

    .table-responsive table {
        font-size: 12.5px !important;
        min-width: 580px !important;
    }

    .table-responsive th,
    .table-responsive td {
        padding: 8px 10px !important;
    }

    /* Toast Container position */
    .pumkin-toast-container {
        top: 88px;
        right: 12px;
        left: 12px;
        width: auto;
    }
}

/* Specific Smartphone Adjustments (<= 480px) */
@media (max-width: 480px) {
    body {
        padding: 0 0 40px 0 !important;
    }

    .wrapper {
        padding: 16px 12px !important;
        border-radius: 10px !important;
        margin-top: 10px !important;
    }

    .pumkin-nav-container {
        padding: 0 8px !important;
        margin-bottom: 8px !important;
    }

    .brand-logo span:first-child {
        font-size: 15px !important;
    }

    .brand-badge {
        font-size: 8.5px !important;
        padding: 1px 4px !important;
    }

    .nav-tab {
        padding: 6px 11px !important;
        font-size: 12px !important;
    }

    .table-responsive table {
        font-size: 12px !important;
        min-width: 540px !important;
    }

    .table-responsive th,
    .table-responsive td {
        padding: 7px 8px !important;
    }

    h1 {
        font-size: 20px !important;
        line-height: 1.3 !important;
    }

    h2 {
        font-size: 17px !important;
        margin-top: 28px !important;
    }

    .filter-panel {
        padding: 12px !important;
    }
}

    
/* ==========================================================================
   PUMKIN REUSABLE EMPTY STATE & LOADING SPINNER COMPONENTS
   ========================================================================== */
.pumkin-empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 48px 24px;
    border-radius: 12px;
    background: var(--card-bg);
    border: 1px dashed var(--border-color);
    color: var(--text-muted);
    margin: 20px 0;
    width: 100%;
    grid-column: 1 / -1;
}

.pumkin-empty-icon {
    font-size: 44px;
    margin-bottom: 12px;
    line-height: 1;
    opacity: 0.9;
}

.pumkin-empty-title {
    font-size: 16px;
    font-weight: 700;
    color: var(--text-main);
    margin-bottom: 6px;
}

.pumkin-empty-desc {
    font-size: 13.5px;
    color: var(--text-muted);
    max-width: 440px;
    line-height: 1.5;
    margin-bottom: 16px;
}

.pumkin-empty-action {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 18px;
    border-radius: 8px;
    background: var(--primary);
    color: #ffffff;
    font-size: 13.5px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.18s ease;
    font-family: inherit;
}

.pumkin-empty-action:hover {
    opacity: 0.92;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.25);
}

.pumkin-loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 48px 20px;
    color: var(--text-muted);
    gap: 14px;
    width: 100%;
    grid-column: 1 / -1;
}

.pumkin-spinner {
    width: 38px;
    height: 38px;
    border: 3.5px solid var(--border-color);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: pumkinSpin 0.75s linear infinite;
}

.pumkin-loading-text {
    font-size: 13.5px;
    font-weight: 500;
    color: var(--text-muted);
}

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

    
/* ==========================================================================
   ENHANCED DARK MODE HARMONIZATION & COMPONENT POLISH
   ========================================================================== */

/* 1. Live Challenge Lobby */
.live-lobby-card {
    max-width: 600px;
    margin: 40px auto;
    padding: 32px 28px;
    background: var(--card-bg);
    border-radius: 14px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.06);
    text-align: center;
    border: 1px solid var(--border-color);
    transition: background-color 0.2s ease, border-color 0.2s ease;
}

body.dark-mode .live-lobby-card {
    background: #121824 !important;
    border-color: #232d3f !important;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.6) !important;
}

body.dark-mode #live-pin-input {
    background: #161f2e !important;
    color: #f1f5f9 !important;
    border-color: #334155 !important;
}

body.dark-mode #live-pin-input:focus {
    border-color: #ea580c !important;
    outline: none;
    box-shadow: 0 0 0 3px rgba(234, 88, 12, 0.2) !important;
}

body.dark-mode #live-host-controls {
    background: #06281e !important;
    border-color: #047857 !important;
}

body.dark-mode #live-host-controls h4 {
    color: #6ee7b7 !important;
}

body.dark-mode #live-host-controls div {
    color: #a7f3d0 !important;
}

body.dark-mode #live-participants-list h4 {
    color: #f1f5f9 !important;
}

body.dark-mode #live-participants-ul li {
    color: #cbd5e1 !important;
    border-bottom-color: #232d3f !important;
}

/* 2. Exam Cards & Meta Sub-boxes */
body.dark-mode .exam-card-meta {
    background: #161f2e !important;
    border: 1px solid #232d3f !important;
    color: #94a3b8 !important;
}

body.dark-mode .exam-card-meta span {
    color: #cbd5e1 !important;
}

body.dark-mode .exam-card-footer {
    border-top: 1px solid #232d3f !important;
}

body.dark-mode .exam-source-tag {
    color: #94a3b8 !important;
}

/* 3. Category & Difficulty Badges in Dark Mode */
body.dark-mode .badge-tsa {
    background: #1e293b !important;
    color: #93c5fd !important;
    border: 1px solid #334155 !important;
}

body.dark-mode .badge-hsa {
    background: #382412 !important;
    color: #fcd34d !important;
    border: 1px solid #78350f !important;
}

body.dark-mode .badge-calc {
    background: #3b1836 !important;
    color: #f5d0fe !important;
    border: 1px solid #701a75 !important;
}

body.dark-mode .diff-easy {
    background: #064e3b !important;
    color: #6ee7b7 !important;
}

body.dark-mode .diff-medium {
    background: #78350f !important;
    color: #fde68a !important;
}

body.dark-mode .diff-hard {
    background: #7f1d1d !important;
    color: #fecaca !important;
}

body.dark-mode .diff-expert {
    background: #4c1d95 !important;
    color: #ddd6fe !important;
}

/* 4. Hide Navbar Scrollbar cleanly on all browsers */
.nav-links {
    scrollbar-width: none !important;
    -ms-overflow-style: none !important;
}

.nav-links::-webkit-scrollbar {
    display: none !important;
    width: 0 !important;
    height: 0 !important;
}

.nav-tab {
    flex-shrink: 0 !important;
    white-space: nowrap !important;
}

body.dark-mode .nav-scroll-arrow {
    background: #161f2e !important;
    border-color: #2b384e !important;
    color: #cbd5e1 !important;
}

body.dark-mode .nav-scroll-arrow:hover {
    background: #ea580c !important;
    border-color: #ea580c !important;
    color: #ffffff !important;
}

/* ==============================================================================
   PUMKIN.DEV LEVEL & EXP SYSTEM STYLES
   ============================================================================== */
.nav-level-badge {
    display: inline-flex;
    align-items: center;
    margin-right: 6px;
}
.level-pill {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.15), rgba(234, 88, 12, 0.15));
    border: 1px solid rgba(245, 158, 11, 0.4);
    padding: 3px 8px;
    border-radius: 16px;
    font-size: 12px;
    font-weight: 700;
    color: #d97706;
    transition: all 0.2s ease;
}
.level-pill:hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(245, 158, 11, 0.25);
}
body.dark-mode .level-pill {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.25), rgba(234, 88, 12, 0.25));
    border-color: rgba(245, 158, 11, 0.5);
    color: #fbbf24;
}
.level-mini-bar {
    width: 28px;
    height: 5px;
    background: rgba(0, 0, 0, 0.1);
    border-radius: 4px;
    overflow: hidden;
}
body.dark-mode .level-mini-bar {
    background: rgba(255, 255, 255, 0.15);
}
.level-mini-fill {
    height: 100%;
    background: linear-gradient(90deg, #f59e0b, #ea580c);
    border-radius: 4px;
    transition: width 0.4s ease;
}

/* User Profile Level Card */
.user-level-profile-card {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.08), rgba(234, 88, 12, 0.08));
    border: 1px solid rgba(245, 158, 11, 0.3);
    border-radius: 10px;
    padding: 14px;
}
body.dark-mode .user-level-profile-card {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.15), rgba(234, 88, 12, 0.15));
    border-color: rgba(245, 158, 11, 0.4);
}
.level-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}
.level-badge-large {
    font-size: 15px;
    font-weight: 800;
    color: #d97706;
}
body.dark-mode .level-badge-large {
    color: #fbbf24;
}
.level-title-text {
    font-size: 12.5px;
    color: var(--text-muted, #64748b);
    margin-top: 2px;
}
.level-total-exp {
    text-align: right;
}
.level-total-exp small {
    display: block;
    font-size: 11px;
    color: var(--text-muted, #64748b);
}
.level-total-exp strong {
    font-size: 14px;
    color: var(--primary, #ea580c);
}
.level-progress-wrapper {
    margin-top: 6px;
}
.level-progress-info {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    margin-bottom: 5px;
    color: var(--text-main, #334155);
}
.level-progress-track {
    width: 100%;
    height: 8px;
    background: rgba(0, 0, 0, 0.08);
    border-radius: 6px;
    overflow: hidden;
}
body.dark-mode .level-progress-track {
    background: rgba(255, 255, 255, 0.12);
}
.level-progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #f59e0b, #ea580c);
    border-radius: 6px;
    transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}
.level-next-hint {
    font-size: 11.5px;
    color: var(--text-muted, #64748b);
    text-align: right;
    margin-top: 4px;
}

/* Result Reward Card */
.exp-reward-card {
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 20px;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.05);
    animation: fadeIn 0.4s ease;
}
.exp-awarded {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.12), rgba(234, 88, 12, 0.08));
    border: 1px solid rgba(245, 158, 11, 0.35);
}
body.dark-mode .exp-awarded {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.2), rgba(234, 88, 12, 0.15));
    border-color: rgba(245, 158, 11, 0.45);
}
.exp-guest-promo {
    display: flex;
    align-items: center;
    gap: 14px;
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.08), rgba(99, 102, 241, 0.08));
    border: 1px dashed rgba(59, 130, 246, 0.4);
}
body.dark-mode .exp-guest-promo {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.15), rgba(99, 102, 241, 0.15));
}
.exp-low-acc {
    display: flex;
    align-items: center;
    gap: 14px;
    background: rgba(148, 163, 184, 0.08);
    border: 1px dashed rgba(148, 163, 184, 0.3);
}
.exp-promo-icon {
    font-size: 28px;
    flex-shrink: 0;
}
.exp-promo-text h4 {
    margin: 0 0 4px 0;
    font-size: 14.5px;
    color: var(--primary, #ea580c);
}
.exp-promo-text p {
    margin: 0;
    font-size: 12.5px;
    color: var(--text-muted, #64748b);
}
.exp-card-body {
    display: flex;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
}
.exp-gain-badge {
    background: linear-gradient(135deg, #f59e0b, #ea580c);
    color: #ffffff;
    border-radius: 12px;
    padding: 10px 16px;
    text-align: center;
    box-shadow: 0 4px 10px rgba(234, 88, 12, 0.3);
    flex-shrink: 0;
}
.exp-plus {
    font-size: 24px;
    font-weight: 800;
    display: block;
    line-height: 1;
}
.exp-unit {
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 1px;
    text-transform: uppercase;
}
.exp-details {
    flex: 1;
    min-width: 220px;
}
.exp-breakdown-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: 10px;
    font-size: 12px;
}
.bonus-tag {
    padding: 2px 7px;
    border-radius: 6px;
    font-weight: 600;
}
.tag-acc { background: rgba(34, 197, 94, 0.15); color: #15803d; border: 1px solid rgba(34, 197, 94, 0.3); }
.tag-hard { background: rgba(234, 88, 12, 0.15); color: #c2410c; border: 1px solid rgba(234, 88, 12, 0.3); }
.tag-hell { background: rgba(168, 85, 247, 0.15); color: #7e22ce; border: 1px solid rgba(168, 85, 247, 0.3); }
.tag-missed { background: rgba(148, 163, 184, 0.15); color: #64748b; border: 1px solid rgba(148, 163, 184, 0.3); }
body.dark-mode .tag-acc { color: #4ade80; }
body.dark-mode .tag-hard { color: #fb923c; }
body.dark-mode .tag-hell { color: #c084fc; }
.exp-bar-container {
    background: rgba(255, 255, 255, 0.6);
    border: 1px solid rgba(0, 0, 0, 0.05);
    border-radius: 8px;
    padding: 8px 10px;
}
body.dark-mode .exp-bar-container {
    background: rgba(0, 0, 0, 0.25);
    border-color: rgba(255, 255, 255, 0.08);
}
.exp-bar-header {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    margin-bottom: 6px;
}
.level-up-banner {
    background: linear-gradient(135deg, #f59e0b, #ea580c);
    color: #ffffff;
    border-radius: 8px;
    padding: 10px 14px;
    margin-bottom: 12px;
    text-align: center;
    box-shadow: 0 4px 12px rgba(234, 88, 12, 0.35);
}
@keyframes popIn {
    0% { transform: scale(0.95); opacity: 0; }
    100% { transform: scale(1); opacity: 1; }
}
/* Deep Learning Button & Crossed Chains Lock */
.btn-deep-learning {
    position: relative;
    overflow: visible;
    padding: 8px 24px;
    font-size: 14.5px;
    font-weight: 800;
    letter-spacing: 0.5px;
    border-radius: 8px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 135px;
    min-height: 40px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    user-select: none;
    line-height: 1;
}

/* NÚT BỊ TỐI MÀU & BỊ KHÓA BỞI 2 DÂY XÍCH (Level <= 3) */
.btn-deep-learning.is-locked {
    background: linear-gradient(135deg, #180507 0%, #350c12 50%, #150305 100%) !important;
    border: 1px solid #7f1d1d !important;
    color: #fecaca !important;
    box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.85), 0 2px 5px rgba(0,0,0,0.4) !important;
    cursor: not-allowed !important;
}

.btn-deep-learning.is-locked:hover {
    background: linear-gradient(135deg, #24070a 0%, #451016 50%, #1c0507 100%) !important;
    box-shadow: inset 0 2px 12px rgba(0, 0, 0, 0.95), 0 0 14px rgba(220, 38, 38, 0.45) !important;
}

/* NÚT ĐƯỢC MỞ KHÓA (Level > 3) */
.btn-deep-learning.is-unlocked {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 50%, #b91c1c 100%) !important;
    border: 1px solid #f87171 !important;
    color: #ffffff !important;
    box-shadow: 0 4px 14px rgba(220, 38, 38, 0.4), inset 0 1px 0 rgba(255, 255, 255, 0.25) !important;
    cursor: pointer !important;
}

.btn-deep-learning.is-unlocked:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(220, 38, 38, 0.6), inset 0 1px 0 rgba(255, 255, 255, 0.35) !important;
}

/* DÂY XÍCH ĐÈ LÊN TRÊN CHỮ (z-index: 2) */
.dl-chains-overlay {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 2;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border-radius: 7px;
}

.btn-deep-learning.is-unlocked .dl-chains-overlay {
    display: none !important;
}

/* CHỮ Ở CHÍNH GIỮA (z-index: 1 - nằm dưới dây xích) */
.dl-label-container {
    position: relative;
    z-index: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    width: 100%;
    color: #ffffff !important;
    text-shadow: 0 1px 4px rgba(0, 0, 0, 0.95), 0 0 4px rgba(0,0,0,0.9);
    font-weight: 800;
    font-size: 14.5px;
    letter-spacing: 0.8px;
}

/* BONG BÓNG CHAT NGAY TRÊN CON TRỎ CHUỘT */
.dl-speech-bubble {
    position: fixed;
    z-index: 999999;
    pointer-events: none;
    background: linear-gradient(135deg, #180507, #2c080d);
    color: #ffffff;
    font-size: 12.5px;
    font-weight: 700;
    padding: 7px 13px;
    border-radius: 8px;
    border: 1px solid #ef4444;
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.6), 0 0 12px rgba(239, 68, 68, 0.4);
    white-space: nowrap;
    transform: translate(-50%, -100%);
    opacity: 0;
    display: none;
    transition: opacity 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    font-family: inherit;
}

/* ĐUÔI BONG BÓNG CHAT (Tam giác chĩa xuống con trỏ chuột) */
.dl-speech-bubble::before {
    content: "";
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 0;
    border-left: 7px solid transparent;
    border-right: 7px solid transparent;
    border-top: 8px solid #ef4444;
}
.dl-speech-bubble::after {
    content: "";
    position: absolute;
    bottom: -7px;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 0;
    border-left: 6px solid transparent;
    border-right: 6px solid transparent;
    border-top: 7px solid #2c080d;
}


/* ==========================================================================
   PERFORMANCE BOOST & EXPANDED UTILITY SCROLLBAR SYSTEM
   ========================================================================== */
:root {
    --scrollbar-size: 11px;
}

/* 1. THANH TRƯỢT TIỆN ÍCH LỚN HƠN & DỄ TƯƠNG TÁC */
::-webkit-scrollbar {
    width: var(--scrollbar-size, 11px);
    height: var(--scrollbar-size, 11px);
}

::-webkit-scrollbar-track {
    background: rgba(0, 0, 0, 0.04);
    border-radius: 6px;
}

body.dark-mode ::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.04);
}

::-webkit-scrollbar-thumb {
    background: #94a3b8;
    border-radius: 6px;
    border: 2px solid transparent;
    background-clip: content-box;
    transition: background-color 0.2s ease;
}

::-webkit-scrollbar-thumb:hover {
    background: #64748b;
    border: 2px solid transparent;
    background-clip: content-box;
}

body.dark-mode ::-webkit-scrollbar-thumb {
    background: #475569;
}

body.dark-mode ::-webkit-scrollbar-thumb:hover {
    background: #64748b;
}

/* Scrollbars cho các khối tiện ích (Formula, Code, Question Grid, Chat) */
.formula-math-box::-webkit-scrollbar,
.formula-latex-box::-webkit-scrollbar,
.nav-grid-box::-webkit-scrollbar,
.vsc-chat-stream::-webkit-scrollbar,
pre::-webkit-scrollbar,
code::-webkit-scrollbar {
    width: 10px !important;
    height: 10px !important;
}

.formula-math-box::-webkit-scrollbar-thumb,
.formula-latex-box::-webkit-scrollbar-thumb,
.nav-grid-box::-webkit-scrollbar-thumb,
.vsc-chat-stream::-webkit-scrollbar-thumb,
pre::-webkit-scrollbar-thumb,
code::-webkit-scrollbar-thumb {
    background: #94a3b8 !important;
    border-radius: 6px !important;
    border: 2px solid transparent !important;
    background-clip: content-box !important;
}

/* THANH TRƯỢT RANGE SLIDER LỚN HƠN DỄ KÉO */
input[type="range"], .pdl-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 10px;
    border-radius: 6px;
    background: #e2e8f0;
    outline: none;
    cursor: pointer;
    margin: 8px 0;
}

body.dark-mode input[type="range"], body.dark-mode .pdl-slider {
    background: #334155;
}

input[type="range"]::-webkit-slider-thumb, .pdl-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: #2563eb;
    border: 2.5px solid #ffffff;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.25);
    cursor: pointer;
    transition: transform 0.15s ease, background-color 0.15s ease;
}

input[type="range"]::-webkit-slider-thumb:hover, .pdl-slider::-webkit-slider-thumb:hover {
    transform: scale(1.15);
    background: #1d4ed8;
}

input[type="range"]::-moz-range-thumb, .pdl-slider::-moz-range-thumb {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: #2563eb;
    border: 2.5px solid #ffffff;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.25);
    cursor: pointer;
}

/* 2. ARTICLE LAYOUT (MỞ RỘNG 100% VÌ ĐÃ BỎ MỤC LỤC) */
.article-layout {
    display: block !important;
    width: 100% !important;
    margin-top: 20px !important;
}

.article-body {
    width: 100% !important;
    max-width: 100% !important;
    box-sizing: border-box !important;
}

.article-toc {
    display: none !important;
}

/* 3. TỐI ƯU HÓA HIỆU NĂNG WEBSITE (FAST RENDERING ENGINE) */
.knowledge-grid, .formula-card-grid, .exam-grid, .qbank-list {
    content-visibility: auto;
    contain-intrinsic-size: auto 350px;
}

.formula-card, .knowledge-card, .qbank-card, .exam-card {
    contain: layout style;
}

* {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}