/* ==========================================================================
   HỆ THỐNG GIAO DIỆN "ÔN LUYỆN" (THEO MẪU THIẾT KẾ DEMO 2026 - 2027)
   Chuẩn hóa cho 3 cấp: Tiểu học (Lớp 1-5), THCS (Lớp 6-9), THPT (Lớp 10-12)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Patrick+Hand&family=Mali:wght@500;600;700&family=Plus+Jakarta+Sans:ital,wght@0,400;0,500;0,600;0,700;0,800;1,400&display=swap');

:root {
    --ol-font-hand: 'Patrick Hand', 'Mali', cursive, sans-serif;
    /* Main Theme - Clean Modern Premium EdTech */
    --ol-primary: #1565c0;        /* Royal Blue */
    --ol-primary-hover: #0d47a1;
    --ol-primary-light: #e3f2fd;
    --ol-accent: #f59e0b;         /* Warm Gold/Amber */
    
    /* Backgrounds */
    --ol-bg: #f8fafc;
    --ol-surface: #ffffff;
    --ol-border: #e2e8f0;
    --ol-border-hover: #cbd5e1;
    
    /* Text */
    --ol-text-title: #0f172a;
    --ol-text-body: #334155;
    --ol-text-muted: #64748b;
    --ol-text-light: #94a3b8;
    
    /* Cấp 1 - Tiểu học (Orange / Warm / Joyful) */
    --ol-c1-primary: #ea580c;
    --ol-c1-bg: #fff7ed;
    --ol-c1-border: #fed7aa;
    --ol-c1-btn: #f97316;
    
    /* Cấp 2 - THCS (Sky Blue / Vibrant) */
    --ol-c2-primary: #0284c7;
    --ol-c2-bg: #f0f9ff;
    --ol-c2-border: #bae6fd;
    --ol-c2-btn: #0284c7;
    
    /* Cấp 3 - THPT (Emerald Mint & Deep Navy) */
    --ol-c3-primary: #059669;
    --ol-c3-bg: #f0fdf4;
    --ol-c3-border: #bbf7d0;
    --ol-c3-btn: #10b981;
    
    /* Shadows & Radii */
    --ol-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --ol-shadow-md: 0 4px 14px -2px rgba(15, 23, 42, 0.07);
    --ol-shadow-lg: 0 10px 25px -4px rgba(15, 23, 42, 0.09);
    --ol-radius-sm: 8px;
    --ol-radius-md: 14px;
    --ol-radius-lg: 20px;
    --ol-radius-full: 9999px;
    
    --ol-font: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: var(--ol-font);
}

html {
    scroll-behavior: smooth;
    text-rendering: optimizeLegibility;
    overflow-x: clip;
    max-width: 100vw;
}

body {
    background-color: var(--ol-bg);
    color: var(--ol-text-body);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    padding-bottom: 3rem;
    overflow-x: clip;
    max-width: 100vw;
}

/* Hardware-accelerated smooth transitions & rendering optimization */
.ol-card-box, .thcs-stat-card, .thpt-stat-card, .ol-btn-primary, .ol-btn-cta, .ol-btn-outline {
    transform: translateZ(0);
    will-change: transform, box-shadow;
}

.ol-chapter-card, #chapter-list .ol-card-box {
    content-visibility: auto;
    contain-intrinsic-size: 0 160px;
}

/* ================= TOP NAVBAR (ZERO WRAP & POLISHED) ================= */
/* ================= TOP NAVBAR (ZERO OVERFLOW & BALANCED) ================= */
.ol-navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--ol-border);
    transition: all 0.2s ease;
    box-shadow: 0 2px 10px rgba(0,0,0,0.03);
    width: 100%;
    box-sizing: border-box;
    overflow-x: clip;
}

.ol-nav-container {
    max-width: 1360px;
    margin: 0 auto;
    padding: 0.5rem 1.25rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    width: 100%;
    box-sizing: border-box;
}

.ol-brand {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    text-decoration: none;
    cursor: pointer;
    flex-shrink: 0;
    white-space: nowrap;
}

.ol-brand-icon {
    width: 38px;
    height: 38px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
    border: 1px solid rgba(0, 0, 0, 0.06);
    background: #ffffff;
    flex-shrink: 0;
    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.ol-brand:hover .ol-brand-icon {
    transform: scale(1.04);
}

.ol-brand-icon img,
.ol-brand-icon svg {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.ol-brand-text {
    white-space: nowrap;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.ol-brand-heading {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    line-height: 1.1;
}

.ol-brand-text h1,
.ol-brand-text .ol-brand-title {
    font-size: 1.22rem;
    font-weight: 800;
    color: #0f172a;
    line-height: 1.1;
    letter-spacing: -0.3px;
    margin: 0;
    display: inline-block;
}

.ol-brand-badge {
    display: inline-flex;
    align-items: center;
    font-size: 0.65rem;
    font-weight: 800;
    color: #0284c7;
    background: #f0f9ff;
    border: 1px solid #bae6fd;
    padding: 0.1rem 0.45rem;
    border-radius: 6px;
    letter-spacing: 0.2px;
    white-space: nowrap;
    line-height: 1.2;
}

.ol-brand-text p,
.ol-brand-tagline {
    font-size: 0.7rem;
    color: #64748b;
    font-weight: 600;
    white-space: nowrap;
    margin: 0.15rem 0 0 0;
    line-height: 1.2;
}

.ol-nav-menu {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    list-style: none;
    margin: 0;
    padding: 0;
    flex-wrap: nowrap;
    flex-shrink: 1;
    min-width: 0;
}

.ol-nav-item {
    white-space: nowrap;
    flex-shrink: 0;
}

.ol-nav-item a {
    text-decoration: none;
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--ol-text-body);
    transition: all 0.15s ease;
    padding: 0.35rem 0.5rem;
    position: relative;
    white-space: nowrap;
    display: inline-flex;
    align-items: center;
    border-radius: 6px;
}

.ol-nav-item a:hover {
    color: var(--ol-primary);
    background: rgba(2, 132, 199, 0.05);
}

.ol-nav-item a.active {
    color: var(--ol-primary);
    background: rgba(2, 132, 199, 0.08);
}

.ol-nav-item a.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 8px;
    right: 8px;
    height: 2px;
    background: var(--ol-primary);
    border-radius: 2px;
}

.ol-nav-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-shrink: 0;
    margin-left: auto;
}

/* Breakpoint 1: Laptops <= 1380px -> hide long tagline */
@media (max-width: 1380px) {
    .ol-brand-tagline {
        display: none !important;
    }
}

/* Breakpoint 2: Small Laptops <= 1220px -> hide secondary anchor tabs & compress spacing */
@media (max-width: 1220px) {
    .ol-nav-item-sub {
        display: none !important;
    }
    .ol-nav-menu {
        gap: 0.2rem;
    }
    .ol-nav-item a {
        font-size: 0.84rem;
        padding: 0.3rem 0.4rem;
    }
}

.ol-nav-search {
    position: relative;
    display: flex;
    align-items: center;
}

.ol-nav-search input {
    background: #f1f5f9;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-full);
    padding: 0.45rem 1rem 0.45rem 2.2rem;
    font-size: 0.85rem;
    width: 200px;
    outline: none;
    transition: all 0.2s ease;
    color: var(--ol-text-title);
}

.ol-nav-search input:focus {
    background: white;
    border-color: var(--ol-primary);
    width: 250px;
    box-shadow: 0 0 0 3px rgba(21, 101, 192, 0.1);
}

.ol-nav-search-icon {
    position: absolute;
    left: 0.75rem;
    color: var(--ol-text-muted);
    font-size: 0.85rem;
    pointer-events: none;
}

.ol-user-badge {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.3rem 0.75rem 0.3rem 0.3rem;
    background: #f8fafc;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-full);
    cursor: pointer;
    transition: all 0.2s ease;
}

.ol-user-badge:hover {
    background: white;
    border-color: var(--ol-primary);
}

.ol-user-avatar {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, #0284c7 0%, #0369a1 100%);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.82rem;
}

.ol-user-info {
    display: flex;
    flex-direction: column;
    text-align: left;
}

.ol-user-name {
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--ol-text-title);
    line-height: 1.1;
}

.ol-user-role {
    font-size: 0.7rem;
    color: var(--ol-text-muted);
    font-weight: 500;
}

/* Study Tabs Switcher */
.ol-study-tabs-container {
    background: white;
    border-bottom: 1px solid var(--ol-border);
    padding: 0.75rem 0;
    margin-bottom: 1.5rem;
}

.ol-study-tabs {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: #f1f5f9;
    padding: 0.35rem;
    border-radius: var(--ol-radius-full);
    width: fit-content;
}

.ol-study-tab {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.55rem 1.35rem;
    border-radius: var(--ol-radius-full);
    border: none;
    background: transparent;
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--ol-text-muted);
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
}

.ol-study-tab:hover {
    color: var(--ol-text-title);
}

.ol-study-tab.active {
    background: white;
    color: var(--ol-primary);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.ol-study-tab.active.tab-thcs {
    color: #0284c7;
}

.ol-study-tab.active.tab-thpt {
    color: #059669;
}

.ol-btn-icon {
    width: 38px;
    height: 38px;
    border-radius: 50%;
    border: 1px solid var(--ol-border);
    background: white;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--ol-text-body);
    font-size: 1rem;
    transition: all 0.2s ease;
}

.ol-btn-icon:hover {
    background: var(--ol-bg);
    border-color: var(--ol-border-hover);
}

.ol-btn-outline {
    padding: 0.5rem 1.15rem;
    border: 1px solid var(--ol-border);
    background: white;
    border-radius: var(--ol-radius-full);
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--ol-text-body);
    cursor: pointer;
    transition: all 0.2s ease;
}

.ol-btn-outline:hover {
    border-color: var(--ol-primary);
    color: var(--ol-primary);
    background: var(--ol-primary-light);
}

.ol-btn-primary {
    padding: 0.5rem 1.35rem;
    background: linear-gradient(135deg, #1976d2 0%, #1565c0 100%);
    border: none;
    border-radius: var(--ol-radius-full);
    font-size: 0.88rem;
    font-weight: 700;
    color: white;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(21, 101, 192, 0.25);
    transition: all 0.2s ease;
}

.ol-btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(21, 101, 192, 0.35);
}

/* ================= MAIN CONTAINER ================= */
.ol-container {
    max-width: 1240px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* ================= HERO BANNER (FULL BLEED BLEMISH-FREE BACKDROP & CRISP OVERLAY) ================= */
.ol-hero-section-full {
    width: 100%;
    background-color: #f0f6ff;
    border-bottom: 1px solid #dbeafe;
    position: relative;
    overflow: hidden;
    min-height: 520px;
    display: flex;
    align-items: center;
    margin-bottom: 2.5rem;
}

.ol-hero-backdrop-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    pointer-events: none;
    overflow: hidden;
}

.ol-hero-backdrop-img {
    position: absolute;
    top: 0;
    right: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: right center;
    transition: opacity 0.35s ease, transform 0.35s ease;
}

.ol-hero-backdrop-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, 
        rgba(240, 246, 255, 0.98) 0%, 
        rgba(240, 246, 255, 0.96) 42%, 
        rgba(240, 246, 255, 0.72) 60%, 
        rgba(240, 246, 255, 0.18) 82%, 
        rgba(240, 246, 255, 0.0) 100%
    );
    z-index: 2;
    pointer-events: none;
}

.ol-hero-container {
    max-width: 1340px;
    width: 100%;
    margin: 0 auto;
    padding: 3.5rem 2rem 3rem;
    position: relative;
    z-index: 5;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.ol-hero-content-left {
    max-width: 650px;
    width: 100%;
}

.ol-hero-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: #0284c7;
    font-size: 0.82rem;
    font-weight: 800;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    margin-bottom: 0.85rem;
    background: rgba(224, 242, 254, 0.85);
    padding: 0.3rem 0.85rem;
    border-radius: 9999px;
    border: 1px solid rgba(186, 230, 253, 0.9);
}

.ol-hero-title {
    font-size: 3.1rem;
    font-weight: 800;
    color: #0f172a;
    line-height: 1.15;
    margin-bottom: 1.15rem;
    letter-spacing: -1.2px;
}

.ol-hero-desc {
    font-size: 1.05rem;
    color: #334155;
    line-height: 1.65;
    margin-bottom: 2rem;
    max-width: 580px;
    text-shadow: 0 1px 2px rgba(255, 255, 255, 0.8);
}

.ol-hero-actions {
    display: flex;
    align-items: center;
    gap: 1.25rem;
    margin-bottom: 2.25rem;
    flex-wrap: wrap;
}

.ol-btn-hero-primary {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.85rem 2.2rem;
    background: #0284c7;
    color: white;
    font-size: 1rem;
    font-weight: 700;
    border-radius: var(--ol-radius-full);
    text-decoration: none;
    box-shadow: 0 8px 24px rgba(2, 132, 199, 0.3);
    transition: all 0.2s ease;
    border: none;
    cursor: pointer;
}

.ol-btn-hero-primary:hover {
    background: #0369a1;
    transform: translateY(-2px);
    box-shadow: 0 10px 28px rgba(2, 132, 199, 0.4);
}

.ol-btn-hero-secondary {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.85rem 1.85rem;
    background: rgba(255, 255, 255, 0.95);
    color: #0284c7;
    font-size: 1rem;
    font-weight: 700;
    border-radius: var(--ol-radius-full);
    text-decoration: none;
    border: 1.5px solid #bae6fd;
    transition: all 0.2s ease;
    cursor: pointer;
}

.ol-btn-hero-secondary:hover {
    background: #ffffff;
    border-color: #0284c7;
}

.ol-hero-stats {
    display: flex;
    align-items: center;
    gap: 2.25rem;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(2, 132, 199, 0.2);
    flex-wrap: wrap;
}

.ol-stat-item {
    position: relative;
}

.ol-stat-item:not(:last-child)::after {
    content: '';
    position: absolute;
    right: -1.15rem;
    top: 15%;
    bottom: 15%;
    width: 1px;
    background: #cbd5e1;
}

.ol-stat-item h3 {
    font-size: 1.75rem;
    font-weight: 800;
    color: #0284c7;
    line-height: 1.1;
}

.ol-stat-item p {
    font-size: 0.82rem;
    color: #475569;
    font-weight: 600;
    margin-top: 0.25rem;
}

/* Floating Handwritten Sticker and Badges */
.ol-hero-floating-decor {
    position: relative;
    align-self: flex-start;
    padding-top: 2rem;
}

.ol-hero-sticker-handwritten {
    font-family: var(--ol-font-hand);
    font-size: 1.5rem;
    color: #0284c7;
    line-height: 1.3;
    font-weight: 700;
    transform: rotate(-4deg);
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(8px);
    border: 1.5px solid #bae6fd;
    padding: 0.65rem 1.15rem;
    border-radius: 16px;
    box-shadow: 0 8px 20px rgba(2, 132, 199, 0.12);
    pointer-events: none;
    max-width: 240px;
    text-align: center;
}

@media (max-width: 992px) {
    .ol-hero-section-full {
        min-height: auto;
    }
    .ol-hero-backdrop-overlay {
        background: linear-gradient(90deg, 
            rgba(240, 246, 255, 0.98) 0%, 
            rgba(240, 246, 255, 0.95) 100%
        );
    }
    .ol-hero-container {
        padding: 2.5rem 1.25rem;
    }
    .ol-hero-title {
        font-size: 2.35rem;
    }
    .ol-hero-floating-decor {
        display: none;
    }
}

/* ================= CẤP HỌC SECTION (EXACT DEMO CARDS) ================= */
.ol-levels-section {
    padding: 2.5rem 0 3.5rem;
}

.ol-section-title {
    text-align: center;
    margin-bottom: 2.5rem;
}

.ol-section-title h2 {
    font-size: 2.2rem;
    font-weight: 800;
    color: #0f172a;
    letter-spacing: -0.5px;
}

.ol-section-title p {
    font-size: 1.05rem;
    color: #64748b;
    margin-top: 0.35rem;
}

.ol-levels-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.75rem;
}

@media (max-width: 992px) {
    .ol-hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    .ol-hero-desc {
        margin-left: auto;
        margin-right: auto;
    }
    .ol-hero-actions {
        justify-content: center;
    }
    .ol-hero-stats {
        justify-content: center;
    }
    .ol-levels-grid {
        grid-template-columns: 1fr;
    }
    .ol-hero-sticker-handwritten {
        left: 10px;
    }
}

.ol-level-card-demo {
    border-radius: 24px;
    padding: 1.65rem 1.75rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1.25rem;
    text-decoration: none;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    cursor: pointer;
    position: relative;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.03);
}

.ol-level-card-demo:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.08);
}

/* Tiểu học */
.ol-level-card-demo.card-c1 {
    background: #fff7ed;
    border: 1.5px solid #fed7aa;
}
.ol-level-card-demo.card-c1:hover,
.ol-level-card-demo.active.card-c1 {
    border-color: #f97316;
    box-shadow: 0 0 0 3px rgba(234, 88, 12, 0.2), 0 8px 20px rgba(234, 88, 12, 0.08);
}

/* THCS */
.ol-level-card-demo.card-c2 {
    background: #f0f9ff;
    border: 1.5px solid #bae6fd;
}
.ol-level-card-demo.card-c2:hover,
.ol-level-card-demo.active.card-c2 {
    border-color: #0284c7;
    box-shadow: 0 0 0 3px rgba(2, 132, 199, 0.2), 0 8px 20px rgba(2, 132, 199, 0.08);
}

/* THPT */
.ol-level-card-demo.card-c3 {
    background: #f0fdf4;
    border: 1.5px solid #bbf7d0;
}
.ol-level-card-demo.card-c3:hover,
.ol-level-card-demo.active.card-c3 {
    border-color: #10b981;
    box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.2), 0 8px 20px rgba(16, 185, 129, 0.08);
}

.ol-level-icon-badge {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.card-c1 .ol-level-icon-badge {
    background: #ffedd5;
}
.card-c2 .ol-level-icon-badge {
    background: #e0f2fe;
}
.card-c3 .ol-level-icon-badge {
    background: #dcfce7;
}

.ol-level-icon-badge img {
    width: 38px;
    height: 38px;
    object-fit: contain;
}

.ol-level-details {
    flex: 1;
}

.ol-level-details h3 {
    font-size: 1.45rem;
    font-weight: 800;
    line-height: 1.1;
    margin: 0;
}

.card-c1 .ol-level-details h3 { color: #9a3412; }
.card-c2 .ol-level-details h3 { color: #0369a1; }
.card-c3 .ol-level-details h3 { color: #15803d; }

.ol-level-grade-badge {
    font-size: 0.92rem;
    font-weight: 700;
    margin: 0.25rem 0 0.4rem 0;
}

.card-c1 .ol-level-grade-badge { color: #c2410c; }
.card-c2 .ol-level-grade-badge { color: #0284c7; }
.card-c3 .ol-level-grade-badge { color: #16a34a; }

.ol-level-details p {
    font-size: 0.85rem;
    color: #64748b;
    line-height: 1.4;
    margin: 0;
}

.ol-level-arrow-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.1rem;
    font-weight: 700;
    flex-shrink: 0;
    transition: transform 0.2s ease;
}

.ol-level-card-demo:hover .ol-level-arrow-btn {
    transform: scale(1.1);
}

.card-c1 .ol-level-arrow-btn { background: #ea580c; }
.card-c2 .ol-level-arrow-btn { background: #0284c7; }
.card-c3 .ol-level-arrow-btn { background: #16a34a; }

    color: var(--ol-text-title);
    margin-bottom: 0.4rem;
    letter-spacing: -0.5px;
}

.ol-section-title p {
    font-size: 0.98rem;
    color: var(--ol-text-muted);
}

.ol-levels-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
}

.ol-level-card {
    background: white;
    border-radius: var(--ol-radius-lg);
    padding: 1.75rem;
    box-shadow: var(--ol-shadow-sm);
    transition: all 0.25s ease;
    cursor: pointer;
    text-decoration: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1.25rem;
    position: relative;
    border: 2px solid transparent;
}

.ol-level-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--ol-shadow-lg);
}

/* Level: Tiểu học */
.ol-level-c1 {
    background: var(--ol-c1-bg);
    border-color: var(--ol-c1-border);
}
.ol-level-c1:hover {
    border-color: var(--ol-c1-primary);
}
.ol-level-c1 .ol-level-icon {
    background: #ffedd5;
    color: var(--ol-c1-primary);
}
.ol-level-c1 .ol-level-badge {
    color: var(--ol-c1-primary);
}
.ol-level-c1 .ol-level-btn {
    background: var(--ol-c1-btn);
}

/* Level: THCS */
.ol-level-c2 {
    background: var(--ol-c2-bg);
    border-color: var(--ol-c2-border);
}
.ol-level-c2:hover {
    border-color: var(--ol-c2-primary);
}
.ol-level-c2 .ol-level-icon {
    background: #e0f2fe;
    color: var(--ol-c2-primary);
}
.ol-level-c2 .ol-level-badge {
    color: var(--ol-c2-primary);
}
.ol-level-c2 .ol-level-btn {
    background: var(--ol-c2-btn);
}

/* Level: THPT */
.ol-level-c3 {
    background: var(--ol-c3-bg);
    border-color: var(--ol-c3-border);
}
.ol-level-c3:hover {
    border-color: var(--ol-c3-primary);
}
.ol-level-c3 .ol-level-icon {
    background: #dcfce7;
    color: var(--ol-c3-primary);
}
.ol-level-c3 .ol-level-badge {
    color: var(--ol-c3-primary);
}
.ol-level-c3 .ol-level-btn {
    background: var(--ol-c3-btn);
}

.ol-level-left {
    display: flex;
    align-items: center;
    gap: 1.15rem;
}

.ol-level-icon {
    width: 58px;
    height: 58px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    flex-shrink: 0;
}

.ol-level-info h3 {
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--ol-text-title);
    line-height: 1.2;
}

.ol-level-badge {
    font-size: 0.9rem;
    font-weight: 700;
    margin-bottom: 0.3rem;
}

.ol-level-info p {
    font-size: 0.85rem;
    color: var(--ol-text-muted);
    line-height: 1.4;
}

.ol-level-btn {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    font-weight: 800;
    flex-shrink: 0;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    transition: transform 0.2s ease;
}

.ol-level-card:hover .ol-level-btn {
    transform: translateX(3px);
}

/* ================= CHỌN LỚP & MÔN HỌC INTERACTIVE ================= */
.ol-view-wrapper {
    background: white;
    border-radius: var(--ol-radius-lg);
    border: 1px solid var(--ol-border);
    padding: 2rem;
    margin: 2rem 0;
    box-shadow: var(--ol-shadow-sm);
}

.ol-sub-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1.25rem;
}

.ol-sub-header h3 {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--ol-text-title);
}

.ol-grade-selector {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}

.ol-grade-btn {
    padding: 0.75rem 1.25rem;
    border: 1.5px solid var(--ol-border);
    background: var(--ol-bg);
    border-radius: var(--ol-radius-md);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--ol-text-title);
    display: flex;
    align-items: center;
    gap: 0.6rem;
    transition: all 0.2s ease;
}

.ol-grade-btn:hover {
    background: white;
    border-color: var(--ol-primary);
}

.ol-grade-btn.active {
    background: var(--ol-primary);
    color: white;
    border-color: var(--ol-primary);
    box-shadow: 0 4px 12px rgba(21, 101, 192, 0.25);
}

.ol-grade-btn .tag-desc {
    font-size: 0.75rem;
    font-weight: 500;
    opacity: 0.8;
}

.ol-subjects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
    gap: 1.25rem;
}

.ol-subject-card {
    background: #ffffff;
    border: 1.5px solid #e2e8f0;
    border-radius: 16px;
    padding: 1.25rem 1.35rem;
    text-decoration: none;
    color: var(--ol-text-title);
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    gap: 1rem;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.02);
    min-height: 140px;
}

.ol-subject-card:hover {
    background: #ffffff;
    border-color: #0284c7;
    transform: translateY(-3px);
    box-shadow: 0 10px 24px rgba(15, 23, 42, 0.08);
}

.ol-subject-card.is-ready {
    background: #ffffff;
    border-color: #bbf7d0;
}

.ol-subject-card.is-ready:hover {
    border-color: #10b981;
    box-shadow: 0 10px 24px rgba(16, 185, 129, 0.12);
}

.ol-subject-card-header {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.ol-subject-icon-box {
    width: 48px;
    height: 48px;
    border-radius: 12px;
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    overflow: hidden;
    font-size: 1.6rem;
}

.ol-subject-icon-box img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.ol-subject-card-titles {
    flex: 1;
    min-width: 0;
}

.ol-subject-card-title {
    font-size: 1.1rem;
    font-weight: 800;
    color: #0f172a;
    line-height: 1.3;
    margin: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.ol-subject-card-meta {
    display: block;
    font-size: 0.8rem;
    color: #64748b;
    font-weight: 500;
    margin-top: 0.2rem;
}

.ol-subject-card-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem;
    padding-top: 0.75rem;
    border-top: 1px solid #f1f5f9;
}

.ol-subject-status {
    font-size: 0.75rem;
    font-weight: 700;
    padding: 0.2rem 0.6rem;
    border-radius: 6px;
    white-space: nowrap;
}

.ol-subject-status.ready {
    background: #dcfce7;
    color: #15803d;
    border: 1px solid #bbf7d0;
}

.ol-subject-status.draft {
    background: #f1f5f9;
    color: #64748b;
    border: 1px solid #e2e8f0;
}

.ol-subject-cta-btn {
    font-size: 0.82rem;
    font-weight: 800;
    padding: 0.35rem 0.75rem;
    border-radius: 8px;
    white-space: nowrap;
    transition: all 0.2s ease;
}

.ol-subject-cta-btn.ready {
    background: #ecfdf5;
    color: #059669;
    border: 1px solid #a7f3d0;
}

.ol-subject-card:hover .ol-subject-cta-btn.ready {
    background: #059669;
    color: #ffffff;
}

.ol-subject-cta-btn.draft {
    background: #f8fafc;
    color: #64748b;
    border: 1px solid #cbd5e1;
}

/* ================= VALUE PROPOSITION ROW ================= */
.ol-features-row {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 1.25rem;
    margin: 3rem 0 1.5rem;
    padding-top: 2rem;
    border-top: 1px solid var(--ol-border);
}

.ol-feature-card {
    text-align: center;
    padding: 1rem 0.5rem;
}

.ol-feature-icon {
    width: 48px;
    height: 48px;
    margin: 0 auto 0.75rem;
    border-radius: 50%;
    background: #e0f2fe;
    color: #0284c7;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.35rem;
}

.ol-feature-card h4 {
    font-size: 0.95rem;
    font-weight: 700;
    color: var(--ol-text-title);
    margin-bottom: 0.35rem;
}

.ol-feature-card p {
    font-size: 0.78rem;
    color: var(--ol-text-muted);
    line-height: 1.45;
}

/* ================= FOOTER ================= */
.ol-footer {
    background: white;
    border-top: 1px solid var(--ol-border);
    padding: 2rem 0;
    margin-top: 3rem;
}

.ol-footer-content {
    max-width: 1240px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1.5rem;
}

.ol-footer-links {
    display: flex;
    gap: 1.5rem;
    list-style: none;
}

.ol-footer-links a {
    text-decoration: none;
    font-size: 0.85rem;
    color: var(--ol-text-muted);
    font-weight: 500;
    transition: color 0.15s ease;
}

.ol-footer-links a:hover {
    color: var(--ol-primary);
}

.ol-footer-copy {
    font-size: 0.85rem;
    color: var(--ol-text-muted);
}

/* Responsive */
@media (max-width: 992px) {
    .ol-hero-card {
        grid-template-columns: 1fr;
    }
    .ol-levels-grid {
        grid-template-columns: 1fr;
    }
    .ol-features-row {
        grid-template-columns: repeat(2, 1fr);
    }
    .ol-nav-menu {
        display: none;
    }
}

/* ==========================================================================
   GIAO DIỆN ĐỒNG BỘ CHO CÁC TRANG CON (BREADCRUMB, LESSON, QUIZ, FLASHCARD, SUBJECT)
   ========================================================================== */

/* Breadcrumbs & Sub-Header Bar */
.ol-subpage-header {
    background: white;
    border-bottom: 1px solid var(--ol-border);
    padding: 1rem 0;
    margin-bottom: 1.5rem;
}

.ol-breadcrumb-container {
    max-width: 1240px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
}

.ol-breadcrumbs {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.88rem;
    color: var(--ol-text-muted);
}

.ol-breadcrumbs a {
    color: var(--ol-text-body);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.15s;
}

.ol-breadcrumbs a:hover {
    color: var(--ol-primary);
}

.ol-breadcrumbs .separator {
    color: var(--ol-text-light);
}

.ol-breadcrumbs .current {
    color: var(--ol-primary);
    font-weight: 700;
}

.ol-btn-back {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.45rem 0.95rem;
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-full);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--ol-text-body);
    text-decoration: none;
    cursor: pointer;
    transition: all 0.2s;
}

.ol-btn-back:hover {
    background: var(--ol-bg);
    border-color: var(--ol-primary);
    color: var(--ol-primary);
}

/* Banner Môn học / Bài học */
.ol-page-banner {
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-lg);
    padding: 1.75rem 2rem;
    margin-bottom: 1.75rem;
    box-shadow: var(--ol-shadow-sm);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1.5rem;
}

.ol-page-banner-info h1 {
    font-size: 1.65rem;
    font-weight: 800;
    color: var(--ol-text-title);
    margin-bottom: 0.35rem;
}

.ol-page-banner-info p {
    font-size: 0.92rem;
    color: var(--ol-text-muted);
}

.ol-badge-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.25rem 0.75rem;
    border-radius: var(--ol-radius-full);
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.ol-badge-blue {
    background: #e0f2fe;
    color: #0369a1;
}

.ol-badge-emerald {
    background: #dcfce7;
    color: #15803d;
}

.ol-badge-orange {
    background: #ffedd5;
    color: #c2410c;
}

/* ================= LESSON PAGE (LAYOUT 2 CỘT HIỆN ĐẠI) ================= */
.ol-lesson-grid {
    display: grid;
    grid-template-columns: 1fr 340px;
    gap: 1.75rem;
    align-items: start;
}

.ol-lesson-main {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.ol-card-box {
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-md);
    padding: 1.75rem;
    box-shadow: var(--ol-shadow-sm);
}

.ol-concept-box {
    background: #f8fafc;
    border-left: 4px solid var(--ol-primary);
    border-radius: 0 var(--ol-radius-sm) var(--ol-radius-sm) 0;
    padding: 1.25rem 1.5rem;
}

.ol-concept-header {
    font-size: 1.1rem;
    font-weight: 800;
    color: var(--ol-primary);
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.ol-formula-box {
    background: #fffbeb;
    border-left: 4px solid #f59e0b;
    border-radius: 0 var(--ol-radius-sm) var(--ol-radius-sm) 0;
    padding: 1.25rem 1.5rem;
}

.ol-formula-header {
    font-size: 1.1rem;
    font-weight: 800;
    color: #b45309;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.ol-keypoint-item {
    display: flex;
    gap: 0.6rem;
    align-items: flex-start;
    margin-bottom: 0.6rem;
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--ol-text-body);
}

.ol-keypoint-bullet {
    color: #f59e0b;
    font-weight: 800;
}

.ol-example-card {
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-md);
    padding: 1.25rem;
    margin-top: 1rem;
}

.ol-example-title {
    font-weight: 800;
    color: var(--ol-primary);
    font-size: 1rem;
    margin-bottom: 0.5rem;
}

.ol-example-prob {
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--ol-text-title);
    margin-bottom: 0.75rem;
}

.ol-example-sol {
    background: #f0fdf4;
    border: 1px solid #bbf7d0;
    border-left: 3px solid #10b981;
    border-radius: var(--ol-radius-sm);
    padding: 1rem 1.25rem;
    font-size: 0.92rem;
    line-height: 1.65;
    color: #1e293b;
}

.ol-lesson-nav-actions {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--ol-border);
    margin-top: 1rem;
}

/* Cột phải: Lộ trình chương */
.ol-sidebar-card {
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-md);
    padding: 1.5rem;
    box-shadow: var(--ol-shadow-sm);
    position: sticky;
    top: 5rem;
}

.ol-sidebar-title {
    font-size: 1.05rem;
    font-weight: 800;
    color: var(--ol-text-title);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.ol-chapter-lessons-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.ol-chapter-lesson-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.65rem 0.85rem;
    border-radius: var(--ol-radius-sm);
    text-decoration: none;
    color: var(--ol-text-body);
    font-size: 0.88rem;
    font-weight: 600;
    transition: all 0.15s;
    border: 1px solid transparent;
}

.ol-chapter-lesson-item:hover {
    background: var(--ol-bg);
    color: var(--ol-primary);
}

.ol-chapter-lesson-item.active {
    background: #eff6ff;
    color: var(--ol-primary);
    border-color: #bfdbfe;
    font-weight: 700;
}

.ol-quick-action-box {
    margin-top: 1.25rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--ol-border);
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
}

/* ================= QUIZ PAGE (PHÒNG LUYỆN TẬP THẨM MỸ) ================= */
.ol-quiz-wrapper {
    max-width: 820px;
    margin: 0 auto;
}

.ol-quiz-topbar {
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-md);
    padding: 1rem 1.5rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: var(--ol-shadow-sm);
}

.ol-quiz-progress-track {
    flex: 1;
    max-width: 320px;
    height: 8px;
    background: #e2e8f0;
    border-radius: var(--ol-radius-full);
    overflow: hidden;
    margin: 0 1rem;
}

.ol-quiz-progress-bar {
    height: 100%;
    background: linear-gradient(90deg, #3b82f6 0%, #10b981 100%);
    width: 0%;
    transition: width 0.3s ease;
}

.ol-question-card {
    background: white;
    border: 1px solid var(--ol-border);
    border-radius: var(--ol-radius-lg);
    padding: 2rem;
    box-shadow: var(--ol-shadow-md);
    margin-bottom: 1.5rem;
}

.ol-question-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.ol-question-text {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--ol-text-title);
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.ol-options-grid {
    display: flex;
    flex-direction: column;
    gap: 0.85rem;
    margin-bottom: 1.5rem;
}

.ol-option-btn {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.25rem;
    background: #f8fafc;
    border: 1.5px solid var(--ol-border);
    border-radius: var(--ol-radius-md);
    font-size: 1rem;
    font-weight: 600;
    color: var(--ol-text-title);
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: left;
    width: 100%;
}

.ol-option-btn:hover:not([disabled]) {
    background: white;
    border-color: var(--ol-primary);
    transform: translateY(-1px);
    box-shadow: var(--ol-shadow-sm);
}

.ol-option-badge {
    width: 34px;
    height: 34px;
    border-radius: 50%;
    background: white;
    border: 1.5px solid var(--ol-border);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 800;
    font-size: 0.95rem;
    color: var(--ol-text-muted);
    flex-shrink: 0;
}

.ol-option-btn.selected .ol-option-badge {
    background: var(--ol-primary);
    color: white;
    border-color: var(--ol-primary);
}

.ol-option-btn.correct {
    background: #f0fdf4 !important;
    border-color: #10b981 !important;
    color: #15803d !important;
}

.ol-option-btn.correct .ol-option-badge {
    background: #10b981;
    color: white;
    border-color: #10b981;
}

.ol-option-btn.wrong {
    background: #fef2f2 !important;
    border-color: #ef4444 !important;
    color: #b91c1c !important;
}

.ol-option-btn.wrong .ol-option-badge {
    background: #ef4444;
    color: white;
    border-color: #ef4444;
}

/* Lời giải 3 bước sư phạm */
.ol-explanation-card {
    background: #f8fafc;
    border: 1px solid #cbd5e1;
    border-radius: var(--ol-radius-md);
    padding: 1.25rem 1.5rem;
    margin-top: 1.25rem;
    animation: fadeIn 0.3s ease;
}

.ol-explanation-step {
    margin-bottom: 0.75rem;
    font-size: 0.92rem;
    line-height: 1.6;
}

.ol-explanation-step strong {
    color: var(--ol-text-title);
    display: block;
    margin-bottom: 0.2rem;
}

/* ================= FLASHCARD PAGE (THẺ LẬT 3D TINH KHÔI) ================= */
.ol-fc-wrapper {
    max-width: 640px;
    margin: 0 auto;
    text-align: center;
}

.ol-fc-card-scene {
    perspective: 1000px;
    width: 100%;
    min-height: 420px;
    height: 460px;
    margin: 1.5rem 0;
    cursor: pointer;
}

.ol-fc-card {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s cubic-bezier(0.4, 0.2, 0.2, 1);
}

.ol-fc-card.is-flipped {
    transform: rotateY(180deg);
}

.ol-fc-face {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden;
    border-radius: var(--ol-radius-lg);
    background: white;
    border: 1.5px solid var(--ol-border);
    box-shadow: var(--ol-shadow-lg);
    display: flex;
    flex-direction: column;
    padding: 1.75rem 2rem;
    box-sizing: border-box;
}

.ol-fc-face--back {
    transform: rotateY(180deg);
    background: linear-gradient(135deg, #ffffff 0%, #f0fdf4 100%);
    border-color: #bbf7d0;
}

.ol-fc-title {
    font-size: clamp(1.1rem, 2.2vw, 1.45rem);
    font-weight: 800;
    color: var(--ol-text-title);
    line-height: 1.5;
}

.ol-fc-back-body {
    width: 100%;
    font-size: 1.02rem;
    line-height: 1.65;
    color: #1e293b;
    text-align: left;
}

.fc-callout-core {
    font-size: 1.05rem;
    font-weight: 600;
    color: #0f172a;
    line-height: 1.6;
    margin-bottom: 0.85rem;
}

.fc-callout-example {
    background: #eff6ff;
    border-left: 4px solid #3b82f6;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    margin: 0.75rem 0;
    font-size: 0.95rem;
    line-height: 1.6;
    color: #1e40af;
    text-align: left;
}

.fc-callout-insight {
    background: #f0fdf4;
    border-left: 4px solid #22c55e;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    margin: 0.75rem 0;
    font-size: 0.95rem;
    line-height: 1.6;
    color: #166534;
    text-align: left;
}

.fc-callout-warning {
    background: #fffbeb;
    border-left: 4px solid #f59e0b;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    margin: 0.75rem 0;
    font-size: 0.95rem;
    line-height: 1.6;
    color: #92400e;
    text-align: left;
}

.fc-callout-solution {
    background: #f8fafc;
    border-left: 4px solid #64748b;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    margin: 0.75rem 0;
    font-size: 0.95rem;
    line-height: 1.6;
    color: #334155;
    text-align: left;
}

.ol-fc-sub {
    font-size: 0.85rem;
    color: var(--ol-text-muted);
    margin-top: 1rem;
}

.ol-fc-controls {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.25rem;
    margin-top: 1.5rem;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 768px) {
    .ol-lesson-grid {
        grid-template-columns: 1fr;
    }
    .ol-page-banner {
        flex-direction: column;
        align-items: flex-start;
    }
}


/* ================= THPT MOBILE RESPONSIVE EXAM BAR ================= */
.thpt-mobile-bottom-bar {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.96);
    backdrop-filter: blur(10px);
    border-top: 1px solid #e2e8f0;
    padding: 0.6rem 1rem;
    z-index: 1000;
    box-shadow: 0 -4px 15px rgba(0,0,0,0.08);
    justify-content: space-between;
    align-items: center;
}

.thpt-mobile-modal-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(15, 23, 42, 0.6);
    backdrop-filter: blur(4px);
    z-index: 1001;
    justify-content: center;
    align-items: flex-end;
}

.thpt-mobile-modal-content {
    background: white;
    width: 100%;
    max-width: 500px;
    max-height: 80vh;
    border-radius: 20px 20px 0 0;
    padding: 1.5rem;
    overflow-y: auto;
    animation: slideUp 0.25s ease-out;
}

@keyframes slideUp {
    from { transform: translateY(100%); }
    to { transform: translateY(0); }
}

@media (max-width: 900px) {
    .thpt-exam-grid {
        grid-template-columns: 1fr !important;
    }
    .thpt-answer-sheet {
        display: none !important; /* Hide static column on mobile */
    }
    .thpt-mobile-bottom-bar {
        display: flex !important;
    }
    body {
        padding-bottom: 5rem !important;
    }
}


/* ==========================================================================
   P0-6: MOBILE BOTTOM TAB BAR & TOUCH TARGETS (WCAG 44x44px)
   ========================================================================== */

/* Chống cuộn ngang ở màn hình hẹp (360px) */
html, body {
    max-width: 100vw;
    overflow-x: hidden;
}

* {
    box-sizing: border-box;
}

/* Nâng touch targets lên tối thiểu 44x44px */
.ol-nav-menu a,
.ol-nav-item a {
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    padding: 0.5rem 0.65rem;
}

button,
.ol-btn-primary,
.ol-btn-outline,
.ol-btn-cta,
.ol-btn-icon,
.ol-btn-back {
    min-height: 44px;
    min-width: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
}

.ol-nav-search input {
    min-height: 44px;
    height: 44px;
    box-sizing: border-box;
}

.ol-user-badge {
    min-height: 44px;
}

/* Link 'Luyện ➔' và 'Khám phá tất cả môn học ➔' touch target */
.ol-touch-target-44 {
    min-height: 44px;
    min-width: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.4rem 0.8rem;
    border-radius: 8px;
    box-sizing: border-box;
}

/* Mobile Bottom Tab Bar */
.ol-bottom-tabbar {
    display: none;
}

@media (max-width: 992px) {
    body {
        padding-bottom: calc(56px + env(safe-area-inset-bottom, 0px)) !important;
    }

    .ol-bottom-tabbar {
        display: flex !important;
        position: fixed;
        bottom: 0;
        left: 0;
        right: 0;
        height: 56px;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        border-top: 1px solid #e2e8f0;
        z-index: 1000;
        padding-bottom: env(safe-area-inset-bottom, 0px);
        align-items: center;
        justify-content: space-around;
        box-shadow: 0 -3px 12px rgba(0, 0, 0, 0.06);
    }

    .ol-tab-item {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        flex: 1;
        height: 100%;
        min-height: 48px;
        text-decoration: none;
        color: #64748b;
        font-size: 0.72rem;
        font-weight: 700;
        position: relative;
        transition: all 0.15s ease;
        gap: 2px;
        -webkit-tap-highlight-color: transparent;
    }

    .ol-tab-item:active,
    .ol-tab-item[aria-current="page"],
    .ol-tab-item.active {
        color: var(--ol-primary, #0284c7) !important;
    }

    .ol-tab-icon {
        font-size: 1.25rem;
        line-height: 1;
    }

    .ol-tab-badge {
        position: absolute;
        top: 4px;
        right: calc(50% - 18px);
        background: #ef4444;
        color: white;
        font-size: 0.65rem;
        font-weight: 800;
        padding: 0.1rem 0.35rem;
        border-radius: 10px;
        min-width: 16px;
        text-align: center;
        line-height: 1.2;
    }

    .thpt-mobile-bottom-bar {
        bottom: calc(56px + env(safe-area-inset-bottom, 0px)) !important;
    }
}


/* ==========================================================================
   P0-6: MOBILE BOTTOM TAB BAR & TOUCH TARGETS (WCAG 44x44px)
   ========================================================================== */

/* Chống cuộn ngang ở màn hình hẹp (360px) */
html, body {
    max-width: 100vw;
    overflow-x: hidden;
}

* {
    box-sizing: border-box;
}

/* Nâng touch targets lên tối thiểu 44x44px */
.ol-nav-menu a,
.ol-nav-item a {
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    padding: 0.5rem 0.65rem;
}

button,
.ol-btn-primary,
.ol-btn-outline,
.ol-btn-cta,
.ol-btn-icon,
.ol-btn-back {
    min-height: 44px;
    min-width: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    box-sizing: border-box;
}

.ol-nav-search input {
    min-height: 44px;
    height: 44px;
    box-sizing: border-box;
}

.ol-user-badge {
    min-height: 44px;
}

/* Link 'Luyện ➔' và 'Khám phá tất cả môn học ➔' touch target */
.ol-touch-target-44 {
    min-height: 44px;
    min-width: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.4rem 0.8rem;
    border-radius: 8px;
    box-sizing: border-box;
}

/* Mobile Bottom Tab Bar */
.ol-bottom-tabbar {
    display: none;
}

@media (max-width: 992px) {
    body {
        padding-bottom: calc(56px + env(safe-area-inset-bottom, 0px)) !important;
    }

    .ol-bottom-tabbar {
        display: flex !important;
        position: fixed;
        bottom: 0;
        left: 0;
        right: 0;
        height: 56px;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        border-top: 1px solid #e2e8f0;
        z-index: 1000;
        padding-bottom: env(safe-area-inset-bottom, 0px);
        align-items: center;
        justify-content: space-around;
        box-shadow: 0 -3px 12px rgba(0, 0, 0, 0.06);
    }

    .ol-tab-item {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        flex: 1;
        height: 100%;
        min-height: 48px;
        text-decoration: none;
        color: #64748b;
        font-size: 0.72rem;
        font-weight: 700;
        position: relative;
        transition: all 0.15s ease;
        gap: 2px;
        -webkit-tap-highlight-color: transparent;
    }

    .ol-tab-item:active,
    .ol-tab-item[aria-current="page"],
    .ol-tab-item.active {
        color: var(--ol-primary, #0284c7) !important;
    }

    .ol-tab-icon {
        font-size: 1.25rem;
        line-height: 1;
    }

    .ol-tab-badge {
        position: absolute;
        top: 4px;
        right: calc(50% - 18px);
        background: #ef4444;
        color: white;
        font-size: 0.65rem;
        font-weight: 800;
        padding: 0.1rem 0.35rem;
        border-radius: 10px;
        min-width: 16px;
        text-align: center;
        line-height: 1.2;
    }

    .thpt-mobile-bottom-bar {
        bottom: calc(56px + env(safe-area-inset-bottom, 0px)) !important;
    }
}


/* P1-4 & P2-1: Accessible Level Cards as real anchors */
a.ol-level-card {
    text-decoration: none;
    color: inherit;
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
}

/* P2-1: Focus-visible for all interactive elements */
a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible,
[tabindex]:focus-visible {
    outline: 2px solid var(--ol-primary, #0284c7);
    outline-offset: 2px;
}

/* P2-1: Support prefers-reduced-motion */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* ================= INSPIRATIONAL TYPOGRAPHY & DEMO BADGES ================= */
.ol-top-badge-strip {
    background: #eff6ff;
    border-bottom: 1px solid #dbeafe;
    padding: 0.4rem 1rem;
    font-size: 0.8rem;
    color: #1e40af;
    text-align: center;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    flex-wrap: wrap;
}

.ol-top-badge-strip .highlight {
    font-weight: 800;
    color: #1d4ed8;
}

.ol-handwritten {
    font-family: var(--ol-font-hand);
    font-size: 1.35rem;
    color: #0284c7;
    line-height: 1.2;
    transform: rotate(-2deg);
    display: inline-block;
}

.ol-hero-quote-sticker {
    position: absolute;
    top: 10px;
    right: -15px;
    background: #ffffff;
    border: 1.5px solid #fed7aa;
    padding: 0.45rem 0.85rem;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(234, 88, 12, 0.15);
    font-family: var(--ol-font-hand);
    font-size: 1.25rem;
    color: #c2410c;
    font-weight: 700;
    transform: rotate(4deg);
    z-index: 5;
    pointer-events: none;
}

.ol-quote-slogan-bar {
    background: linear-gradient(90deg, #f0fdf4 0%, #eff6ff 50%, #fdf4ff 100%);
    border: 1px dashed #cbd5e1;
    border-radius: 16px;
    padding: 1rem 1.5rem;
    margin: 2.5rem 0;
    display: flex;
    align-items: center;
    justify-content: space-around;
    gap: 1rem;
    flex-wrap: wrap;
    text-align: center;
}

.ol-slogan-step {
    font-size: 0.88rem;
    font-weight: 800;
    color: #334155;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.ol-slogan-step span.icon {
    font-size: 1.2rem;
}

.ol-slogan-sep {
    color: #94a3b8;
    font-weight: 400;
}

/* ==========================================================
   CONTENT PROTECTION & ANTI-COPY SUITE (N&Mstudio Education)
   ========================================================== */
body, 
.ol-container, 
body,
.thpt-container, 
.thcs-container, 
.thpt-exam-grid, 
.thpt-question-body, 
.thpt-opt-btn, 
.ol-card-box, 
.ol-fc-card-scene, 
.ol-fc-face, 
.thcs-layout-grid, 
.review-card {
    -webkit-user-select: none !important;
    -moz-user-select: none !important;
    -ms-user-select: none !important;
    user-select: none !important;
    -webkit-touch-callout: none !important;
}

/* Cho phép bôi đen chọn chữ trong các ô nhập liệu của học sinh */
input, 
textarea, 
[contenteditable="true"] {
    -webkit-user-select: text !important;
    -moz-user-select: text !important;
    -ms-user-select: text !important;
    user-select: text !important;
}

/* Chống kéo thả hình ảnh */
img {
    -webkit-user-drag: none;
    -moz-user-drag: none;
    user-drag: none;
}

/* Chống in ấn và xuất PDF trái phép */
@media print {
    html, body {
        display: none !important;
        visibility: hidden !important;
    }
}

/* ================= THPT TRACK COMBINATION SELECTOR ================= */
.ol-track-box {
    background: #ffffff;
    border: 1.5px solid #e2e8f0;
    border-radius: 16px;
    padding: 1.25rem 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 4px 14px rgba(0, 0, 0, 0.03);
}
.ol-track-chips-wrapper {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin: 0.85rem 0 1rem 0;
}
.ol-track-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 0.95rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 700;
    background: #f8fafc;
    color: #334155;
    border: 1.5px solid #cbd5e1;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    white-space: nowrap;
}
.ol-track-chip:hover {
    background: #f1f5f9;
    border-color: #94a3b8;
    transform: translateY(-1px);
}
.ol-track-chip.active {
    background: #0284c7;
    color: #ffffff;
    border-color: #0284c7;
    box-shadow: 0 4px 12px rgba(2, 132, 199, 0.25);
}
.ol-subject-card.is-track-subject {
    border-color: #0284c7 !important;
    background: linear-gradient(180deg, #ffffff 0%, #f0f9ff 100%) !important;
    box-shadow: 0 4px 14px rgba(2, 132, 199, 0.12) !important;
}
.ol-track-pill {
    background: #dbeafe;
    color: #1d4ed8;
    font-size: 0.72rem;
    font-weight: 800;
    padding: 0.2rem 0.55rem;
    border-radius: 6px;
    border: 1px solid #bfdbfe;
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
}
.ol-track-dimmed {
    opacity: 0.45;
    filter: grayscale(0.6);
}