/* Reset và thiết lập cơ bản */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    overflow-x: hidden; /* Ngăn scroll ngang cho toàn trang */
    scroll-behavior: smooth; /* Smooth scrolling */
}

body {
    font-family: 'Be Vietnam Pro', sans-serif;
    font-size: 14px;
    line-height: 1.6;
    color: #333;
    overflow-x: hidden; /* Ngăn scroll ngang */
    overflow-y: auto; /* Cho phép scroll dọc và hiển thị scrollbar */
    min-height: 100vh;
}

/* Optional overlay for page-content instead of body */
.page-content::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(126, 8, 9, 0.3);
    z-index: 1;
    pointer-events: none;
}

/* Page content wrapper for transitions */
.page-content {
    opacity: 1;
    transform: translateY(0);
    transition: all 0.8s ease-out;
    padding-top: 80px; /* Add padding to account for fixed header */
    background: url('../images/courses/v525_609.png') center/cover no-repeat fixed;
    min-height: calc(100vh - 160px);
    position: relative;
}

.page-content.show {
    opacity: 1;
    transform: translateY(0);
    background: url('../images/courses/v525_609.png') center/cover no-repeat fixed;
}

/* Direct page load - no transition */
.page-content.direct-load {
    opacity: 1;
    transform: translateY(0);
    background: url('../images/courses/v525_609.png') center/cover no-repeat fixed;
    transition: none;
    padding-top: 80px; /* Maintain padding for direct load */
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header - Copied from main.css */
.header {
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: all 0.6s ease-out;
    opacity: 0;
    transform: translateY(-20px);
}

.header.header-visible {
    opacity: 1;
    transform: translateY(0);
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.nav-left {
    display: flex;
    align-items: center;
    gap: 40px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 20px;
}

.ar-button {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 24px;
    background: linear-gradient(135deg, #7E0809 0%, #a31012 100%);
    color: white;
    text-decoration: none;
    border-radius: 25px;
    font-weight: 600;
    font-size: 15px;
    box-shadow: 0 4px 15px rgba(126, 8, 9, 0.3);
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.ar-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(126, 8, 9, 0.4);
    background: linear-gradient(135deg, #a31012 0%, #7E0809 100%);
}

.ar-button:active {
    transform: translateY(0);
    box-shadow: 0 2px 10px rgba(126, 8, 9, 0.3);
}

.ar-button svg {
    width: 20px;
    height: 20px;
}

.logo {
    display: flex;
    align-items: center;
}

.logo-image {
    height: 58px;
    width: auto;
    object-fit: contain;
    cursor: pointer;
    transition: transform 0.3s ease;
}

.logo-image:hover {
    transform: scale(1.05);
}

.logo-text {
    font-size: 24px;
    font-weight: 700;
    color: #d62829;
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-link {
    text-decoration: none;
    color: #333;
    font-weight: 500;
    padding: 10px 20px;
    border-radius: 8px;
    transition: all 0.3s ease;
    font-size: 16px;
}

.nav-link.active {
    background-color: rgba(252, 194, 74, 0.4);
    color: #333;
}

.nav-link:hover {
    background-color: rgba(252, 194, 74, 0.4);
    color: #333;
}

.auth-buttons {
    display: flex;
    gap: 15px;
}

/* User Account Button */
.user-account {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    background: #7E0809;
    color: #fff;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    font-weight: 500;
}

.user-account:hover {
    background: #a10a0b;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(126, 8, 9, 0.3);
}

.user-icon {
    width: 20px;
    height: 20px;
}

/* Hide mobile auth buttons on desktop */
.mobile-auth-buttons {
    display: none;
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    padding: 10px;
    border: none;
    background: none;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: #333;
    margin: 3px 0;
    transition: 0.3s;
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(-45deg) translate(-5px, 6px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(45deg) translate(-5px, -6px);
}

/* Courses Section - Now transparent with global background */
.courses-section {
    padding: 80px 0 50px 0;
    margin-top: 0; /* Remove margin since page-content has padding-top */
    position: relative;
    background: none; /* Remove background - use global background */
    width: 100vw;
    margin-left: calc(-50vw + 50%);
    overflow: hidden; /* Ngăn scroll ngang từ các phần tử con */
    z-index: 2; /* Above page-content overlay */
}

.courses-section::before {
    display: none; /* Remove overlay since we have global overlay */
}

/* Slider wrapper to control overflow while allowing hover effects */
.slider-wrapper {
    position: relative;
    overflow: hidden; /* Hide horizontal scroll */
    padding: 50px 0; /* Extra padding for center-based scaling */
}

.hero-content {
    position: relative;
    z-index: 3;
    text-align: center;
    margin-bottom: 25px; /* Giảm khoảng cách từ 40px xuống 25px */
}

.hero-title {
    color: white;
    font-size: clamp(20px, 3.5vw, 32px); /* Giảm font size từ clamp(24px, 4vw, 40px) */
    font-weight: 700;
    text-align: center;
    margin: 0;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.courses-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 25px 50px;
    display: flex;
    justify-content: center; /* Center the 3 cards */
    gap: 40px; /* Larger gap for better spacing with 3 cards */
    overflow: visible;
    scroll-behavior: smooth;
    position: relative;
    z-index: 2;
    white-space: nowrap;
    transition: transform 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    will-change: transform;
    backface-visibility: hidden;
}



/* Slider Controls - Hidden for 3-card layout (no sliding needed) */
.slider-controls {
    display: none; /* Hide controls since we only have 3 cards that fit on screen */
}

.slider-btn {
    background: rgba(255, 255, 255, 0.95);
    border: none;
    border-radius: 50%;
    width: 55px;
    height: 55px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    pointer-events: auto;
    color: #333;
    opacity: 0.8;
    backdrop-filter: blur(10px);
}

.slider-btn:hover {
    background: rgba(252, 194, 74, 0.95);
    transform: scale(1.15);
    box-shadow: 0 8px 30px rgba(252, 194, 74, 0.3);
    color: #fff;
    opacity: 1;
}

.slider-btn:active {
    transform: scale(1.05);
    transition: transform 0.1s ease;
}

.slider-btn svg {
    transition: transform 0.3s ease;
}

.slider-btn:hover svg {
    transform: scale(1.2);
}

/* Simple fade transition for smooth experience */
.slide-transition {
    transition: opacity 0.6s ease-in-out, transform 0.6s ease-in-out;
}

/* Hero Section - Now integrated as background for courses */
.hero-section {
    display: none; /* Hidden since background is now part of courses section */
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('../images/v99_261.png') center/cover no-repeat;
    z-index: 1;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(126, 8, 9, 0.8);
    z-index: 2;
}

.hero-content {
    position: relative;
    z-index: 3;
    text-align: center;
}

.hero-title {
    color: #fff;
    font-size: clamp(32px, 5vw, 48px);
    font-weight: 700;
    margin: 0;
}

/* Course Card - Enhanced smooth transitions with center-based scaling */
.course-card {
    position: relative;
    min-width: 320px; /* Larger cards for 3-card layout */
    max-width: 320px;
    height: 420px; /* Taller for better proportion */
    border-radius: 15px;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    flex-shrink: 0;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
    will-change: transform;
    z-index: 10;
    transform-origin: center center;
}

.course-card:hover {
    transform: scaleY(1.15) scaleX(1.08); /* Kéo dài chiều cao hơn chiều rộng */
    z-index: 200; /* Highest priority when hovering */
}

.card-image {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 1;
    overflow: hidden;
}

.card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: all 0.4s ease;
    filter: grayscale(100%) brightness(0.7);
}

/* Đảm bảo ảnh luôn đen trắng khi không hover */
.course-card:not(:hover) .card-image img {
    filter: grayscale(100%) brightness(0.7) !important;
    transform: scale(1) !important;
}

.course-card:hover .card-image img {
    filter: grayscale(0%) brightness(1);
    transform: scale(1.1);
}

.card-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(
        to bottom,
        rgba(0, 0, 0, 0.2) 0%,
        rgba(0, 0, 0, 0.5) 50%,
        rgba(0, 0, 0, 0.8) 100%
    );
    z-index: 2;
    transition: all 0.4s ease;
}

/* Đảm bảo overlay luôn đen khi không hover */
.course-card:not(:hover) .card-overlay {
    background: linear-gradient(
        to bottom,
        rgba(0, 0, 0, 0.2) 0%,
        rgba(0, 0, 0, 0.5) 50%,
        rgba(0, 0, 0, 0.8) 100%
    ) !important;
}

.course-card:hover .card-overlay {
    background: linear-gradient(
        to bottom,
        rgba(252, 194, 74, 0.2) 0%,
        rgba(252, 194, 74, 0.6) 50%,
        rgba(252, 194, 74, 0.9) 100%
    );
}

.card-content {
    position: absolute;
    bottom: 15px;
    left: 20px;
    right: 20px;
    z-index: 3;
    color: white;
    text-align: left;
    transform: translateY(30px);
    opacity: 0;
    transition: all 0.4s ease;
    min-height: 60px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
}

/* Đảm bảo content luôn ẩn khi không hover */
.course-card:not(:hover) .card-content {
    transform: translateY(30px) !important;
    opacity: 0 !important;
}

.course-card:hover .card-content {
    transform: translateY(0);
    opacity: 1;
}

.period {
    display: block;
    color: #333;
    font-size: clamp(10px, 1.6vw, 12px);
    font-weight: 600;
    margin-bottom: 5px;
    transition: all 0.4s ease;
}

.title {
    color: #7E0809;
    font-size: clamp(10px, 1.6vw, 14px); /* Giảm từ clamp(12px, 2vw, 18px) */
    font-weight: 700;
    margin-bottom: 6px; /* Giảm từ 8px xuống 6px */
    line-height: 1.2; /* Giảm từ 1.3 xuống 1.2 */
    word-wrap: break-word;
    overflow-wrap: break-word;
    word-break: break-word;
    hyphens: auto;
    white-space: normal;
    max-width: 100%;
    transition: all 0.4s ease;
    text-shadow: none;
}

.course-card:hover .title {
    font-size: clamp(11px, 1.7vw, 15px); /* Giảm từ clamp(13px, 2.1vw, 19px) */
    line-height: 1.2; /* Giảm từ 1.3 xuống 1.2 */
}

.duration {
    color: #333;
    font-size: clamp(10px, 1.7vw, 12px);
    font-weight: 500;
    margin: 0;
    transition: all 0.4s ease;
}

/* Additional responsive breakpoints */
@media (max-width: 1200px) {
    .course-card {
        min-width: 280px;
        max-width: 280px;
        height: 380px;
    }
    
    .courses-container {
        gap: 30px;
    }

    .title {
        font-size: clamp(10px, 1.6vw, 14px);
        line-height: 1.2;
        word-break: break-word;
        white-space: normal;
    }

    .course-card:hover .title {
        font-size: clamp(11px, 1.7vw, 15px);
        line-height: 1.2;
    }
}

@media (max-width: 992px) {
    .course-card {
        min-width: 260px;
        max-width: 260px;
        height: 350px;
    }
    
    .courses-container {
        gap: 25px;
    }

    .title {
        font-size: clamp(9px, 1.5vw, 13px);
        line-height: 1.2;
        word-break: break-word;
        white-space: normal;
    }

    .course-card:hover .title {
        font-size: clamp(10px, 1.6vw, 14px);
        line-height: 1.2;
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    body {
        background-attachment: scroll; /* Tắt fixed background trên mobile */
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .nav-left {
        gap: 20px;
    }
    
    .header {
        flex-wrap: wrap;
    }
    
    .header-right {
        order: -1;
        margin-right: auto;
    }
    
    .ar-button {
        padding: 8px 16px;
        font-size: 13px;
    }
    
    .ar-button svg {
        width: 16px;
        height: 16px;
    }
    
    .ar-button span {
        display: none;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        background-color: white;
        flex-direction: column;
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        transition: left 0.3s ease;
        padding: 20px 0;
        z-index: 1001;
        max-height: calc(100vh - 70px);
        overflow-y: auto;
    }
    
    .nav-menu.mobile-active {
        left: 0;
    }
    
    .nav-menu li {
        width: 100%;
        text-align: center;
    }
    
    .nav-link {
        display: block;
        padding: 15px 20px;
        width: 100%;
    }

    .courses-section {
        padding: 70px 0 40px 0;
        margin-top: 0;
        margin-left: 0;
        width: 100%;
    }

    .hero-title {
        font-size: clamp(20px, 3vw, 28px);
        margin-bottom: 30px;
    }

    .hero-section {
        height: 300px;
    }

    .courses-container {
        gap: 20px;
        padding: 0 20px;
        max-width: 100%;
        justify-content: flex-start; /* Allow scroll on mobile */
        overflow-x: auto;
        overflow-y: visible;
        scroll-snap-type: x mandatory;
        -webkit-overflow-scrolling: touch; /* Smooth scrolling on iOS */
        scrollbar-width: none; /* Hide scrollbar on Firefox */
    }
    
    /* Hide scrollbar on Chrome, Safari, and Opera */
    .courses-container::-webkit-scrollbar {
        display: none;
    }

    .course-card {
        min-width: 280px;
        max-width: 280px;
        height: 360px;
        scroll-snap-align: center;
        flex-shrink: 0;
    }
    
    /* Hide slider controls on mobile */
    .slider-controls {
        display: none;
    }
    
    /* Adjust slider wrapper for mobile scrolling */
    .slider-wrapper {
        overflow: visible;
        padding: 30px 0;
    }

    .title {
        font-size: clamp(9px, 1.6vw, 14px);
        line-height: 1.3;
        word-break: break-word;
        white-space: normal;
    }

    .course-card:hover .title {
        font-size: clamp(10px, 1.7vw, 15px);
        line-height: 1.3;
    }

    .period,
    .duration {
        font-size: clamp(8px, 1.3vw, 10px);
    }

    .card-content {
        bottom: 12px;
        left: 15px;
        right: 15px;
        min-height: 55px;
    }
}

@media (max-width: 480px) {
    body {
        background-attachment: scroll;
    }
    
    .header .container {
        padding: 10px 15px;
    }
    
    .courses-section {
        margin-top: 0;
        padding: 50px 0 30px 0;
        margin-left: 0;
        width: 100%;
    }

    .hero-title {
        font-size: clamp(18px, 4vw, 24px);
        margin-bottom: 25px;
    }

    .courses-container {
        gap: 15px;
        padding: 0 15px;
    }

    .course-card {
        min-width: 260px;
        max-width: 260px;
        height: 340px;
        scroll-snap-align: center;
    }

    .card-content {
        bottom: 12px;
        left: 12px;
        right: 12px;
        min-height: 50px;
    }

    .title {
        font-size: clamp(9px, 1.5vw, 13px);
        line-height: 1.3;
        margin-bottom: 4px;
        word-break: break-word;
        white-space: normal;
    }

    .course-card:hover .title {
        font-size: clamp(10px, 1.6vw, 14px);
        line-height: 1.3;
    }

    .period,
    .duration {
        font-size: clamp(8px, 1.3vw, 10px);
    }
}

/* Responsive logo sizing */
@media (max-width: 768px) {
    .logo-image {
        height: 35px;
    }
}

/* Course Detail Section */
.course-detail-section {
    background-color: #f5f5f5;
    padding: 60px 0;
    margin-top: auto;
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease-out;
    position: relative;
    /* Ẩn scrollbar chỉ cho Course Detail Section */
    scrollbar-width: none; /* Firefox */
    -ms-overflow-style: none; /* IE and Edge */
    overflow: hidden;
}

.course-detail-section::-webkit-scrollbar {
    display: none; /* Chrome, Safari, Opera */
}

.course-detail-section.show {
    opacity: 1;
    transform: translateY(0);
}

.course-detail-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 500px;
    scrollbar-width: none;
    -ms-overflow-style: none;
}

.course-detail-container::-webkit-scrollbar {
    display: none; /* Chrome, Safari, Opera */
}

/* Left side - Content */
.course-detail-left {
    padding-right: 0;
    display: flex;
    gap: 20px;
    justify-content: space-between;
}

.timeline-and-year {
    display: flex;
    flex-direction: column;
    gap: 30px;
    flex-shrink: 0;
}

.course-year-title {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
}

.year-large {
    font-size: 55px;
    font-weight: 500;
    color: #7E0909;
    line-height: 1;
}

.year-small {
    display: flex;
    color: #7E0909;
    flex-direction: column;
    gap: -5px;
}

.year-top {
    font-size: 22px;
    font-weight: 600;
    color: #7E0909;
    line-height: 1;
}

.year-bottom {
    font-size: 22px;
    font-weight: 600;
    color: #7E0909;
    line-height: 1;
}

.course-period {
    font-size: 18px;
    font-weight: 500;
    color: #7E0909;
    margin-left: 20px;
    padding-left: 20px;
    border-left: 3px solid #7E0909;
    display: flex;
    flex-direction: column;
    line-height: 1.3;
    gap: 0;
    min-width: 139px;
    width: 139px;
}

/* Lesson content */
.lesson-content {
    max-width: 1200px;
    width: 100%;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 30px;
    padding: 20px;
}

/* Video Title */
.video-title {
    font-size: 36px;
    font-weight: 700;
    color: #7E0809;
    text-align: center;
    margin: 0;
    line-height: 1.3;
    font-family: 'Be Vietnam Pro', sans-serif;
}

.start-lesson-btn {
    background-color: #7E0809;
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 300;
    cursor: pointer;
    transition: all 0.3s ease;
    align-self: center;
}

.start-lesson-btn:hover {
    background-color: #a10a0b;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(126, 8, 9, 0.3);
}

/* Timeline */
.timeline-container {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin-top: 0;
}

.timeline-item {
    display: flex;
    color: #B8B8B8;
    align-items: center;
    gap: 15px;
    padding: 8px 0;
    cursor: pointer;
}

.timeline-item.active .timeline-year {
    color: #7F0909;
    font-weight: 600;
}

.timeline-icon {
    width: 20px;
    height: 20px;
}

.timeline-year {
    font-size: 14px;
    color: #666;
    font-weight: 500;
}

/* Right side - Image */
.course-detail-right {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding-left: 0;
    overflow: visible; /* Đổi về visible để overlay hiển thị */
    position: relative;
    padding: 40px 60px 20px 0;
    margin: -40px -60px -20px 0;
    min-height: 400px; /* Đặt chiều cao tối thiểu để tránh thay đổi đột ngột */
}

.lesson-image-container {
    position: relative;
    width: 100%;
    max-width: 360px;
    z-index: 2;
    transition: transform 0.6s cubic-bezier(0.4, 0.0, 0.2, 1), opacity 0.4s ease;
    will-change: transform, opacity;
    overflow: visible;
}

.lesson-image {
    width: 100%;
    height: auto;
    aspect-ratio: 3/4;
    object-fit: cover;
    border-radius: 12px;
    position: relative;
    z-index: 2;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.15);
}

.image-year-overlay {
    position: absolute;
    top: -30px;
    right: -39px;
    background: transparent;
    border: none;
    padding: 0;
    font-size: 58px;
    font-weight: bold;
    color: transparent;
    -webkit-text-stroke: 2px #7F0909;
    z-index: 10;
    line-height: 1;
    text-shadow: none;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    overflow: visible;
}

/* Footer */
.footer {
    background-color: #333;
    color: white;
    padding: 20px 0;
    text-align: center;
    margin-top: auto;
}

.footer .container {
    max-width: 1200px;
    margin: 0 auto;
}

/* Responsive design */
@media (max-width: 768px) {
    .course-detail-container {
        grid-template-columns: 1fr;
        gap: 40px;
        padding: 0 20px;
    }
    
    .course-detail-left {
        padding-right: 0;
        flex-direction: column;
        gap: 30px;
    }
    
    .timeline-and-year {
        flex-direction: row;
        gap: 20px;
        align-items: flex-start;
    }
    
    .course-detail-right {
        padding: 20px 40px 10px 0;
        margin: -20px -40px -10px 0;
        order: -1;
    }
    
    .course-year-title {
        justify-content: center;
        margin-bottom: 0;
    }
    
    .lesson-title {
        font-size: 36px;
        text-align: center;
    }
    
    .lesson-content {
        text-align: center;
    }
    
    .title-underline {
        width: 50%;
        margin: 15px auto 20px auto;
        margin-right: 0;
    }
    
    .timeline-container {
        margin-top: 0;
    }
    
    .lesson-image-container {
        max-width: 280px;
        margin: 0 auto;
        padding: 40px 30px 0 0;
    }
    
    .image-year-overlay {
        top: -20px;
        right: -25px;
        font-size: 36px;
        -webkit-text-stroke: 2px #7F0909;
        text-align: center;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .course-detail-section {
        padding: 40px 0;
    }
    
    .course-detail-container {
        gap: 30px;
        padding: 0 15px;
    }
    
    .course-detail-left {
        gap: 20px;
    }
    
    .timeline-and-year {
        flex-direction: column;
        gap: 15px;
    }
    
    .year-large {
        font-size: 56px;
    }
    
    .year-top, .year-bottom {
        font-size: 20px;
    }
    
    .course-period {
        font-size: 16px;
        margin-left: 15px;
    }
    
    .lesson-title {
        font-size: 28px;
    }
    
    .lesson-description {
        font-size: 16px;
    }
    
    .lesson-image-container {
        max-width: 240px;
        padding: 35px 25px 0 0;
    }
    
    .image-year-overlay {
        top: -25px;
        right: -20px;
        font-size: 32px;
        -webkit-text-stroke: 2px #7F0909;
        text-align: center;
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
    }
}

/* ==================== YouTube Frame Styles ==================== */
.youtube-frame-container {
    width: 100%;
    max-width: 100%;
    margin: 0;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
    background: #000;
}

.youtube-frame-container iframe {
    display: block;
    width: 100%;
    height: 450px;
    border: none;
}

/* ==================== Quote Block Styles ==================== */
.quote-block {
    display: flex;
    align-items: flex-start;
    gap: 60px;
    margin: 0;
    padding: 60px 80px;
    position: relative;
    width: 100%;
    max-width: 100%;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    overflow: visible;
}

.quote-block.reverse {
    flex-direction: row-reverse;
}

.quote-image-container {
    flex: 0 0 320px;
    position: relative;
    z-index: 1;
}

.quote-image-container img {
    width: 100%;
    height: 380px;
    object-fit: cover;
    border-radius: 12px;
    position: relative;
    z-index: 2;
}

/* Ngôi sao đỏ sau ảnh Hồ Chí Minh */
.quote-block .quote-image-container::after {
    content: "★";
    position: absolute;
    top: -65%;
    right: -20%;
    font-size: 480px;
    color: #7F0909;
    transform: rotate(30deg);
    z-index: -1;
    opacity: 0.9;
}

/* Hình tròn vàng sau ảnh Võ Nguyên Giáp */
.quote-block.reverse .quote-image-container::after {
    content: "";
    position: absolute;
    top: 35px;
    left: -9px;
    width: 305px;
    height: 305px;
    background: #FCC34A;
    border-radius: 50%;
    z-index: -1;
}

.quote-content-container {
    flex: 1;
    padding: 20px 0;
}

.quote-section-title {
    font-size: 24px;
    font-weight: 600;
    color: #7F0909;
    margin-bottom: 25px;
    margin-left: 30px;
    position: relative;
}

.quote-text-box {
    padding: 25px 30px;
    position: relative;
}

/* Dấu ngoặc kép lớn màu vàng */
.quote-text-box::before {
    content: '❝';
    position: absolute;
    top: -20px;
    left: 20px;
    font-size: 80px;
    color: #FCC34A;
    font-weight: bold;
    line-height: 1;
    z-index: 2;
}

.quote-text-box p {
    font-size: 28px;
    font-style: italic;
    font-weight: 500;
    color: #333;
    margin: 0;
    line-height: 1.6;
}

/* Responsive Design for Quote Block and YouTube */
@media (max-width: 768px) {
    .lesson-content {
        max-width: 100%;
        padding: 10px;
    }

    .video-title {
        font-size: 24px;
        padding: 0 10px;
    }

    .youtube-frame-container {
        margin: 20px 0;
    }

    .youtube-frame-container iframe {
        height: 300px;
    }

    .quote-block,
    .quote-block.reverse {
        flex-direction: column;
        gap: 25px;
        padding: 30px 20px;
        margin: 40px 10px 30px;
        overflow: visible;
    }

    .quote-image-container {
        flex: none;
        align-self: center;
        max-width: 250px;
    }

    .quote-image-container img {
        height: 250px;
    }

    /* Điều chỉnh ngôi sao trên mobile */
    .quote-block .quote-image-container::after {
        font-size: 300px;
        top: -60%;
        right: -16%;
    }

    .quote-block.reverse .quote-image-container::after {
        display: none;
    }

    .quote-section-title {
        font-size: 18px;
        margin-left: 10px;
        text-align: center;
    }

    .quote-text-box {
        padding: 20px 10px;
    }

    .quote-text-box::before {
        font-size: 50px;
        top: -10px;
        left: 5px;
    }

    .quote-text-box p {
        font-size: 16px;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .video-title {
        font-size: 20px;
    }

    .youtube-frame-container iframe {
        height: 220px;
    }

    .quote-block {
        padding: 20px 15px;
        margin: 30px 5px 20px;
    }

    .quote-image-container {
        max-width: 200px;
    }

    .quote-image-container img {
        height: 200px;
    }

    /* Điều chỉnh ngôi sao cho màn hình 480px */
    .quote-block .quote-image-container::after {
        font-size: 250px;
        top: -60%;
        right: -15%;
    }

    .quote-text-box p {
        font-size: 14px;
    }

    .quote-section-title {
        font-size: 16px;
    }

    .quote-text-box::before {
        font-size: 40px;
    }
}

/* ==================== Quiz Content Protection Styles ==================== */
.content-section.quiz-protected,
.vsk-interactive-quiz.quiz-protected,
.final-quote-section.quiz-protected,
.completion-section.quiz-protected,
#protected-content.quiz-protected {
    filter: blur(15px);
    opacity: 0.8;
    pointer-events: none;
    transition: all 0.6s ease;
    position: relative;
}

/* Loại trừ lock overlay khỏi blur effect */
.quiz-protected .lock-overlay-container,
.quiz-protected .lock-overlay-content {
    filter: none !important;
    opacity: 1 !important;
    pointer-events: auto !important;
    z-index: 999 !important;
}

/* Overlay che phủ để tạo hiệu ứng blur */
.content-section.quiz-protected::before,
.vsk-interactive-quiz.quiz-protected::before,
.final-quote-section.quiz-protected::before,
.completion-section.quiz-protected::before,
#protected-content.quiz-protected::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.2);
    z-index: 99;
}

.content-section.quiz-protected::after,
.vsk-interactive-quiz.quiz-protected::after,
.final-quote-section.quiz-protected::after,
.completion-section.quiz-protected::after,
#protected-content.quiz-protected::after {
    content: "Học phần đã bị khóa, trả lời câu hỏi để tiếp tục bài học";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: rgba(255, 255, 255, 1);
    padding: 20px 30px;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 600;
    color: #7F0909;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
    text-align: center;
    white-space: nowrap;
    z-index: 100;
    filter: none;
    opacity: 1;
    pointer-events: auto;
}

.content-section.quiz-unlocked,
.vsk-interactive-quiz.quiz-unlocked,
.final-quote-section.quiz-unlocked,
.completion-section.quiz-unlocked,
#protected-content.quiz-unlocked {
    filter: none;
    opacity: 1;
    pointer-events: auto;
    transition: all 0.6s ease;
}

/* Lock overlay content styles */
.lock-overlay-content {
    background: transparent !important;
    border-radius: 16px;
    padding: 40px 30px;
    text-align: center;
    z-index: 999 !important;
    min-width: 350px;
    max-width: 500px;
    filter: none !important;
    opacity: 1 !important;
    pointer-events: auto !important;
}

.lock-overlay-title {
    color: #7F0909;
    font-size: 18px;
    font-weight: 600;
    line-height: 1.4;
    margin-top: 30%;
    margin-bottom: 24px;
}

.lock-overlay-icon {
    width: 80px;
    height: 80px;
    margin: 20px auto;
    display: block;
}

.lock-overlay-button {
    background: #FCC34A;
    color: #000;
    border: none;
    padding: 14px 28px;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(243, 156, 18, 0.3);
    min-width: 140px;
    margin-top: 20px;
}

.lock-overlay-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(243, 156, 18, 0.4);
}

.lock-overlay-button:active {
    transform: translateY(0);
}

/* ==================== Font Face ==================== */
@font-face {
    font-family: 'NVN Yellost';
    src: url('../font/NVN Yellost-Regular VH.ttf') format('truetype');
    font-weight: normal;
    font-style: normal;
    font-display: swap;
}

/* ==================== Interactive Quiz Styles (from course5.jsp) ==================== */
.vsk-interactive-quiz {
    margin: 120px auto 0;
    padding: 80px 32px 90px;
    background: rgba(250, 228, 182, 0.92);
    border-radius: 0;
    box-shadow: 0 24px 48px rgba(0, 0, 0, 0.08);
    width: 100%;
    max-width: 1200px;
    opacity: 1 !important;
    visibility: visible !important;
    display: block !important;
}

.vsk-interactive-quiz .vsk-quiz-wrapper {
    max-width: 1080px;
    margin: 0 auto;
    padding: 0 32px;
}

.vsk-interactive-quiz .vsk-quiz-header {
    margin-bottom: 40px;
}

.vsk-interactive-quiz .vsk-quiz-title {
    font-family: 'NVN Yellost', cursive;
    font-size: 48px;
    font-weight: 500;
    color: #7F0909;
    text-transform: uppercase;
    letter-spacing: 2px;
    margin: 0;
    text-align: center;
}

.vsk-interactive-quiz .vsk-quiz-body {
    max-width: 1080px;
    margin: 0 auto;
}

.vsk-interactive-quiz .vsk-quiz-question {
    margin-bottom: 48px;
}

.vsk-interactive-quiz .vsk-quiz-question p {
    font-size: 20px;
    font-weight: 500;
    color: #2c2c2c;
    margin-bottom: 24px;
    text-align: center;
}

.vsk-interactive-quiz .vsk-quiz-choices {
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-template-rows: 1fr 1fr;
    gap: 20px;
    margin-bottom: 32px;
}

.vsk-interactive-quiz .vsk-quiz-choice {
    position: relative;
    display: flex;
    align-items: center;
    gap: 18px;
    padding: 18px 36px;
    border: 2px solid transparent;
    border-radius: 18px;
    background: #ffffff;
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08);
    color: #2c2c2c;
    font-size: 16px;
    font-weight: 500;
    text-align: left;
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
    cursor: pointer;
    min-height: 72px;
    opacity: 1 !important;
    visibility: visible !important;
}

.vsk-interactive-quiz .vsk-quiz-choice input[type="radio"] {
    appearance: none;
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border: 2px solid #B8B8B8;
    border-radius: 50%;
    background-color: transparent;
    flex-shrink: 0;
    transition: all 0.3s ease;
    cursor: pointer;
}

.vsk-interactive-quiz .vsk-quiz-choice input[type="radio"]:checked {
    background-color: #FFC700;
    border-color: #FFC700;
}

.vsk-interactive-quiz .vsk-quiz-choice:hover {
    transform: translateY(-2px);
    border-color: #FFC700;
    box-shadow: 0 20px 36px rgba(255, 199, 0, 0.28);
}

.vsk-interactive-quiz .vsk-quiz-choice:hover input[type="radio"] {
    border-color: #FFC700;
}

.vsk-interactive-quiz .vsk-quiz-choice.selected {
    border-color: #FFC700;
    box-shadow: 0 16px 28px rgba(255, 199, 0, 0.25);
}

.vsk-interactive-quiz .vsk-quiz-choice-text {
    flex: 1;
    line-height: 1.5;
}

.vsk-interactive-quiz .vsk-quiz-submit {
    padding: 20px 60px;
    border: none;
    border-radius: 12px;
    background: linear-gradient(135deg, #fcc24a, #ffb400);
    color: #7F0909;
    font-size: 18px;
    font-weight: 700;
    cursor: pointer;
    box-shadow: 0 16px 32px rgba(252, 194, 74, 0.35);
    transition: transform 0.25s ease, box-shadow 0.25s ease;
    display: block;
    margin: 0 auto;
}

.vsk-interactive-quiz .vsk-quiz-submit:hover {
    transform: translateY(-2px);
    box-shadow: 0 20px 38px rgba(252, 194, 74, 0.45);
}

.vsk-interactive-quiz .vsk-quiz-submit:active {
    transform: translateY(0);
}

.vsk-interactive-quiz .vsk-quiz-submit-text {
    display: block;
}

/* Quiz Result Styles */
.vsk-interactive-quiz .vsk-quiz-result {
    margin-top: 32px;
    padding: 30px;
    border-radius: 16px;
    text-align: center;
    animation: slideInUp 0.5s ease;
}

.vsk-interactive-quiz .vsk-quiz-result.correct {
    background: linear-gradient(135deg, #61BA47, #4a9c35);
    color: white;
}

.vsk-interactive-quiz .vsk-quiz-result.incorrect {
    background: linear-gradient(135deg, #FF6B6B, #FF5252);
    color: white;
}

.vsk-interactive-quiz .vsk-quiz-result .result-icon {
    font-size: 48px;
    margin-bottom: 16px;
    font-weight: bold;
}

.vsk-interactive-quiz .vsk-quiz-result .result-message {
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 16px;
}

.vsk-interactive-quiz .vsk-quiz-result .result-explanation {
    font-size: 16px;
    line-height: 1.6;
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid rgba(255, 255, 255, 0.3);
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Responsive Quiz Styles */
@media (max-width: 768px) {
    .vsk-interactive-quiz {
        margin: 80px auto 0;
        padding: 60px 20px 70px;
        border-radius: 24px;
    }

    .vsk-interactive-quiz .vsk-quiz-title {
        font-size: 40px;
        margin-bottom: 32px;
    }

    .vsk-interactive-quiz .vsk-quiz-question p {
        font-size: 18px;
        margin-bottom: 20px;
    }

    .vsk-interactive-quiz .vsk-quiz-choices {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .vsk-interactive-quiz .vsk-quiz-choice {
        padding: 16px 20px;
        gap: 16px;
        min-height: 68px;
    }

    .vsk-interactive-quiz .vsk-quiz-submit {
        width: 100%;
        padding: 16px 40px;
        font-size: 16px;
    }

    .vsk-interactive-quiz .vsk-quiz-result .result-message {
        font-size: 20px;
    }
}

@media (max-width: 480px) {
    .vsk-interactive-quiz {
        margin: 60px auto 0;
        padding: 40px 15px 50px;
    }

    .vsk-interactive-quiz .vsk-quiz-title {
        font-size: 32px;
        letter-spacing: 1px;
    }

    .vsk-interactive-quiz .vsk-quiz-question p {
        font-size: 16px;
        line-height: 1.4;
    }

    .vsk-interactive-quiz .vsk-quiz-choice {
        padding: 14px 18px;
        gap: 14px;
        min-height: 64px;
        font-size: 15px;
    }

    .vsk-interactive-quiz .vsk-quiz-choice input[type="radio"] {
        width: 18px;
        height: 18px;
    }

    .vsk-interactive-quiz .vsk-quiz-result {
        padding: 25px 20px;
    }

    .vsk-interactive-quiz .vsk-quiz-result .result-icon {
        font-size: 36px;
    }

    .vsk-interactive-quiz .vsk-quiz-result .result-message {
        font-size: 18px;
    }

    .vsk-interactive-quiz .vsk-quiz-result .result-explanation {
        font-size: 14px;
    }
}

/* ==================== Final Quote Section (for card-2) ==================== */
.final-quote-section-card2 {
    max-width: 1200px;
    width: 100%;
    background: linear-gradient(135deg, #7F0909, #c41e1e);
    padding: 60px 0;
    margin: 80px auto 0 auto;
    position: relative;
    overflow: hidden;
    border-radius: 0;
}

.final-quote-section-card2::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="25" cy="25" r="1" fill="%23ffffff" opacity="0.1"/><circle cx="75" cy="75" r="1" fill="%23ffffff" opacity="0.08"/></svg>') repeat;
    pointer-events: none;
}

.final-quote-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
    text-align: center;
    position: relative;
    z-index: 2;
}

.final-quote-content {
    position: relative;
}

.final-quote-marks {
    font-size: 60px;
    color: #FCC34A;
    opacity: 0.8;
    position: absolute;
    line-height: 1;
}

.final-quote-marks.opening {
    top: -10px;
    left: -30px;
}

.final-quote-marks.closing {
    bottom: 60px;
    right: -30px;
}

.final-quote-text {
    font-size: 32px;
    font-style: italic;
    font-weight: 400;
    color: white;
    line-height: 1.4;
    margin: 30px 0;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.final-quote-author {
    font-size: 20px;
    font-weight: 600;
    color: #FCC34A;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-top: 30px;
    display: block;
}

/* Responsive for Final Quote Section */
@media (max-width: 768px) {
    .final-quote-section-card2 {
        padding: 40px 0;
        margin: 60px auto 0;
    }

    .final-quote-text {
        font-size: 24px;
        padding: 0 20px;
    }

    .final-quote-marks {
        font-size: 40px;
    }

    .final-quote-marks.opening {
        left: -10px;
    }

    .final-quote-marks.closing {
        right: -10px;
        bottom: 40px;
    }

    .final-quote-author {
        font-size: 16px;
    }
}

@media (max-width: 480px) {
    .final-quote-section-card2 {
        padding: 30px 0;
        margin: 40px auto 0;
    }

    .final-quote-text {
        font-size: 20px;
    }

    .final-quote-marks {
        font-size: 32px;
    }

    .final-quote-author {
        font-size: 14px;
    }
}