.intro-popup-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100vh;
    background: #000;
    display: none;
    z-index: 9999999;
    opacity: 0;
    transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    overflow: hidden;
    backdrop-filter: blur(0px);
}

.intro-popup-overlay.active {
    display: block;
    opacity: 1;
    backdrop-filter: blur(2px);
}

.intro-scroll-container {
    width: 100%;
    height: 100vh;
    overflow-y: scroll;
    scroll-snap-type: y mandatory;
    scroll-behavior: smooth;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none; /* Firefox */
    -ms-overflow-style: none; /* IE/Edge */
}

    /* Hide scrollbar but keep functionality */
    .intro-scroll-container::-webkit-scrollbar {
        display: none;
    }

.intro-scroll-container {
    -ms-overflow-style: none;
    scrollbar-width: none;
}

.intro-slide {
    width: 100%;
    height: 100vh;
    scroll-snap-align: start;
    scroll-snap-stop: always;
    position: relative;
    display: flex;
    flex-direction: column; /* Xếp theo chiều dọc */
    align-items: center; /* Căn giữa ngang */
    justify-content: flex-start; /* Căn lên trên */
    padding-top: 80px; /* Khoảng cách từ đỉnh */
    gap: 30px; /* Khoảng cách giữa ảnh và text */
    transition: transform 0.2s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    transform-origin: center center;
    /* Background mờ */
    background-image: url('/media/thu-ngo/bg.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    background-attachment: fixed;
}

    /* Overlay mờ cho background */
    .intro-slide::before {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: rgba(0, 0, 0, 0.05); /* Overlay đậm để tạo contrast */
        z-index: 1;
    }

    /* Đảm bảo content nằm trên overlay */
    .intro-slide > * {
        position: relative;
        z-index: 2;
    }

    /* Background blur effect - tạo hiệu ứng mờ cho background */
    .intro-slide::after {
        content: '';
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background: inherit;
        background-image: inherit;
        background-size: inherit;
        background-position: inherit;
        filter: blur(10px) brightness(0.6) saturate(0.9);
        z-index: 0;
        transform: scale(1.05); /* Phóng to nhẹ để tránh viền trắng */
    }

    .intro-slide img {
        max-width: 80%; /* Thu nhỏ ảnh để hiển thị đầy đủ */
        max-height: 70vh; /* Giới hạn chiều cao để không che */
        object-fit: contain; /* Hiển thị toàn bộ nội dung ảnh */
        border-radius: 20px;
        box-shadow: 0 20px 50px rgba(0, 0, 0, 0.8); /* Shadow đậm hơn */
        transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
        filter: brightness(1.2) contrast(1.1) saturate(1.1); /* Làm ảnh nổi bật hơn */
        flex-shrink: 0; /* Không co lại */
        border: 3px solid rgba(255, 255, 255, 0.2); /* Viền trắng mờ */
    }

.intro-slide-content {
    background: rgba(0, 0, 0, 0.85); /* Đậm hơn một chút */
    padding: 10px 15px; /* Padding lớn hơn */
    border-radius: 20px; /* Bo góc lớn hơn */
    color: white;
    text-align: center;
    backdrop-filter: blur(15px); /* Blur mạnh hơn */
    border: 2px solid rgba(255, 255, 255, 0.3); /* Viền rõ hơn */
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.7); /* Shadow đậm hơn */
    max-width: 90%;
    flex-shrink: 0; /* Không co lại */
    margin-bottom: 20px; /* Khoảng cách từ đáy */
}

    .intro-slide-content h2 {
        font-size: 22px;
        font-weight: 700;
        margin-bottom: 15px;
        text-shadow: 2px 2px 8px rgba(0,0,0,0.8);
        animation: slideUp 0.8s ease;
        background: linear-gradient(135deg, #ffffff 0%, #f0f0f0 100%);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        background-clip: text;
    }

    .intro-slide-content p {
        font-size: 20px;
        margin-bottom: 0;
        text-shadow: 1px 1px 4px rgba(0,0,0,0.8);
        animation: slideUp 0.8s ease 0.2s backwards;
        max-width: 800px;
        margin: 0 auto;
    }

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.intro-popup-close {
    position: fixed;
    top: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.2);
    border: 2px solid rgba(255, 255, 255, 0.8);
    border-radius: 50%;
    cursor: pointer;
    z-index: 10000;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    color: white;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

    .intro-popup-close:hover {
        background: rgba(255, 255, 255, 0.9);
        color: #333;
        transform: rotate(90deg) scale(1.1);
    }

.intro-scroll-indicator {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 10000;
    display: flex;
    flex-direction: column;
    align-items: center;
    color: white;
    animation: bounce 2s infinite;
    pointer-events: none;
}

    .intro-scroll-indicator.hidden {
        opacity: 0;
        transition: opacity 0.3s ease;
    }

    .intro-scroll-indicator span {
        font-size: 14px;
        margin-bottom: 10px;
        text-shadow: 1px 1px 3px rgba(0,0,0,0.8);
    }

    .intro-scroll-indicator svg {
        width: 30px;
        height: 30px;
        filter: drop-shadow(1px 1px 3px rgba(0,0,0,0.8));
    }

@keyframes bounce {
    0%, 100% {
        transform: translateX(-50%) translateY(0);
    }

    50% {
        transform: translateX(-50%) translateY(10px);
    }
}

.intro-progress-bar {
    position: fixed;
    top: 0;
    left: 0;
    height: 4px;
    background: linear-gradient(90deg, #607e3a 0%, #4f6830 50%, #607e3a 100%);
    background-size: 200% 100%;
    width: 0%;
    z-index: 10001;
    transition: width 0.3s ease;
    animation: progressShine 2s ease-in-out infinite;
    box-shadow: 0 2px 10px rgba(96, 126, 58, 0.5);
}

@keyframes progressShine {
    0% {
        background-position: 200% 0;
    }

    100% {
        background-position: -200% 0;
    }
}

.intro-slide-number {
    position: fixed;
    top: 30px;
    left: 30px;
    color: white;
    font-size: 18px;
    font-weight: 600;
    z-index: 10000;
    text-shadow: 1px 1px 3px rgba(0,0,0,0.8);
    background: rgba(0, 0, 0, 0.6);
    padding: 8px 16px;
    border-radius: 20px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

    .intro-slide-number:hover {
        background: rgba(0, 0, 0, 0.8);
        transform: scale(1.05);
    }

/* Registration Button */
.intro-register-btn {
    display: inline-block;
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a24 100%);
    color: white;
    text-decoration: none;
    padding: 20px 40px;
    border-radius: 50px;
    font-size: 20px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    box-shadow: 0 10px 30px rgba(255, 107, 107, 0.4);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}

    .intro-register-btn:hover {
        transform: translateY(-3px) scale(1.05);
        box-shadow: 0 15px 40px rgba(255, 107, 107, 0.6);
        background: linear-gradient(135deg, #ff5252 0%, #d63031 100%);
    }

    .intro-register-btn:active {
        transform: translateY(-1px) scale(1.02);
    }

    .intro-register-btn span {
        display: block;
        font-size: 18px;
        margin-bottom: 5px;
    }

    .intro-register-btn small {
        display: block;
        font-size: 12px;
        opacity: 0.9;
        font-weight: 400;
    }

    /* Button animation */
    .intro-register-btn::before {
        content: '';
        position: absolute;
        top: 0;
        left: -100%;
        width: 100%;
        height: 100%;
        background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
        transition: left 0.5s;
    }

    .intro-register-btn:hover::before {
        left: 100%;
    }

@media (max-width: 768px) {
    .intro-slide {
        padding-top: 60px;
        gap: 20px;
    }

        .intro-slide img {
            max-width: 90%;
            max-height: 40vh;
        }

    .intro-slide-content {
        padding: 15px 20px;
        margin-bottom: 10px;
    }

        .intro-slide-content h2 {
            font-size: 24px;
        }

        .intro-slide-content p {
            font-size: 14px;
        }

    .intro-popup-close {
        width: 45px;
        height: 45px;
        top: 20px;
        right: 20px;
        font-size: 24px;
    }

    .intro-slide-number {
        top: 20px;
        left: 20px;
        font-size: 16px;
    }

    .intro-scroll-indicator {
        bottom: 30px;
    }

    .intro-register-btn {
        padding: 15px 30px;
        font-size: 16px;
    }
}

@media (max-width: 576px) {
    .intro-slide-content {
        padding: 30px 20px 50px;
    }

        .intro-slide-content h2 {
            font-size: 24px;
        }

        .intro-slide-content p {
            font-size: 14px;
        }
}