.section-title {
        font-size: 2.5rem; /* 40px */
        margin-bottom: 1rem; /* 16px */
        position: relative;
        padding-bottom: 0.5rem; /* 8px */
    }
    .section-title::after {
        content: '';
        position: absolute;
        bottom: 0;
        left: 50%;
        transform: translateX(-50%);
        width: 100px;
        height: 3px;
        background-color: #64ffda;
    }
    /* For left-aligned titles */
    #intro-section .section-title::after {
        left: 0;
        transform: translateX(0);
    }
            /* --- Hero Section --- */
    .hero-section {
        position: relative;
        height: 100vh;
        display: flex;
        align-items: center;
        justify-content: center;
        text-align: center;
        color: #ffffff;
        overflow: hidden;
    }
    .hero-bg {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    z-index: 1;
    filter: brightness(0.6) contrast(1.1);
    transition: transform 1s ease;
    }

    .hero-section:hover .hero-bg {
    transform: scale(1.05);
    }

    #hero-video-background{
        position: absolute;
        top: 50%;
        left: 50%;
        min-width: 100%;
        min-height: 100%;
        width: auto;
        height: auto;
        transform: translate(-50%, -50%);
        z-index: 1;
        object-fit: cover; /* Ensures video covers the area */
    }

    .hero-overlay {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0, 0, 0, 0.6);
        z-index: 2;
    }

    .hero-content {
        position: absolute;
        z-index: 3;
        max-width: 800px;
        padding: 20px;
    }

    .hero-content h1 {
        font-size: 3.8rem; /* ~60px */
        font-weight: 700;
        margin-bottom: 20px;
        letter-spacing: 1px;
        text-shadow: 2px 2px 8px rgba(0,0,0,0.7);
    }

    .hero-content .subtitle {
        font-size: 1.3rem; /* ~21px */
        margin-bottom: 35px;
        font-weight: 300;
        line-height: 1.7;
        color: var(--light-text);
    }

    .cta-button { /* This is an <a> tag styled as a button */
        background-color: var(--accent-color);
        color: var(--dark-bg);
        padding: 15px 40px;
        font-size: 1.1rem; /* ~18px */
        font-weight: 600;
        border: none;
        border-radius: 50px;
        text-transform: uppercase;
        cursor: pointer;
        transition: background-color 0.3s ease, transform 0.3s ease, box-shadow 0.3s ease;
        text-decoration: none;
        display: inline-block;
        box-shadow: 0 4px 15px rgba(100, 255, 218, 0.3);
    }

    .cta-button:hover {
        background-color: #52d1bc;
        color: var(--dark-bg);
        transform: translateY(-3px);
        box-shadow: 0 6px 20px rgba(100, 255, 218, 0.4);
        text-decoration: none;
    }

    /* Scroll Down Indicator */
    .scroll-down-indicator {
        position: absolute; /* Định vị tuyệt đối */
        bottom: 30px; /* Cách đáy 30px */
        left: 50%; /* Căn giữa theo chiều ngang */
        transform: translateX(-50%); /* Điều chỉnh để căn giữa chính xác */
        z-index: 3; /* Đặt ở lớp trên cùng */
        opacity: 0.7; /* Độ mờ */
        width: 30px; /* Chiều rộng */
        height: 50px; /* Chiều cao */
        border: 2px solid var(--glow-color-1); /* Viền */
        border-radius: 15px; /* Bo tròn góc */
        display: inline-block;
        transition: opacity var(--transition-fast), border-color var(--transition-fast); /* Transition cho độ mờ và màu viền */
    }
    .scroll-down-indicator::before {
        content: ''; /* Tạo nội dung rỗng */
        position: absolute; /* Định vị tuyệt đối bên trong indicator */
        top: 8px; /* Vị trí từ trên xuống */
        left: 50%; /* Căn giữa theo chiều ngang */
        width: 4px; /* Chiều rộng */
        height: 10px; /* Chiều cao */
        background: var(--glow-color-1); /* Màu nền */
        border-radius: 2px; /* Bo tròn góc */
        animation: scroll-anim 2s infinite; /* Animation hiệu ứng cuộn */
        transition: background-color var(--transition-fast); /* Transition cho màu nền */
    }
    .scroll-down-indicator:hover { opacity: 1; border-color: var(--glow-color-3); } /* Hiển thị rõ hơn và đổi màu viền khi hover */
    .scroll-down-indicator:hover::before { background: var(--glow-color-3); } /* Đổi màu chấm tròn khi hover */

    @keyframes scroll-anim {
        0% { transform: translateX(-50%) translateY(0); opacity: 1; }
        50% { transform: translateX(-50%) translateY(20px); opacity: 0; }
        100% { transform: translateX(-50%) translateY(0); opacity: 1; }
    }

    /*---Cho hiệu ứng cuộn---*/
    .animate-on-scroll {
        opacity: 0;
        transform: translateY(30px);
        transition: opacity 0.8s ease-out, transform 0.8s ease-out;
    }

    .animate-on-scroll.is-visible {
        opacity: 1;
        transform: translateY(0);
    }

    /* --- Featured Highlights Section --- */
    .featured-highlights-section {
        background-color: var(--dark-bg); /* Consistent with body or slightly different if needed */
    }
    .custom-card {
        background-color: var(--card-bg);
        border: 1px solid var(--border-color);
        color: var(--light-text);
        transition: transform 0.3s ease, box-shadow 0.3s ease;
    }
    .custom-card:hover {
        transform: translateY(-10px);
        box-shadow: 0 10px 30px rgba(0,0,0,0.2);
    }
    .custom-card .card-title {
        color: #e6f1ff;
        font-size: 1.5rem; /* ~24px */
    }
    .custom-card .card-text {
        color: #c0c0c0;
        font-size: 0.95rem; /* ~15px */
    }
    .custom-card .card-img-top {
        height: 200px;
        object-fit: cover;
    }

    /* --- Secondary CTA Section --- */
    .cta-secondary-section {
        background-size: cover;
        background-position: center center;
        background-attachment: fixed; /* Parallax effect */
        color: #ffffff;
        position: relative;
    }
    .cta-overlay { /* Overlay for readability on CTA background image */
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(10, 25, 47, 0.7); /* Dark overlay */
        z-index: 1;
    }
    .cta-secondary-section .container {
        z-index: 2; /* Content above overlay */
    }
    .cta-secondary-section .section-title, .cta-secondary-section .lead {
        color: #ffffff;
    }
    .cta-secondary-section .btn-light {
        color: var(--dark-bg);
    }
    .cta-secondary-section .btn-light:hover {
        background-color: #f0f0f0;
    }
        .universe-content p, .universe-content li {
            font-size: 1.1rem;
            line-height: 1.7;
            color: #c0c0c0; /* Màu chữ hơi xám hơn */
        }
        .universe-content strong {
            color: #e0e0e0;
        }

        /* Card Styling */
        .card-universe {
            background-color: #0a0a1f; /* Nền card sẫm hơn */
            border: 1px solid #223366; /* Viền card */
            border-radius: 10px;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            overflow: hidden; /* Để bo tròn ảnh */
        }

        .card-universe:hover {
            transform: translateY(-8px);
            box-shadow: 0 8px 25px rgba(51, 204, 255, 0.3);
        }

        .card-universe img {
            height: 220px;
            object-fit: cover;
            border-bottom: 1px solid #223366;
        }

        .card-universe .card-body {
            color: #b0b0c0;
        }

        .card-universe .card-title {
            color: #66ccff; /* Màu tiêu đề card sáng hơn */
            font-weight: 600;
        }
        .card-universe .btn-outline-info {
            color: #66ccff;
            border-color: #66ccff;
        }
        .card-universe .btn-outline-info:hover {
            background-color: #66ccff;
            color: #000011;
        }

        /* Modal Styling */
        .modal-content {
            background-color: #070718;
            margin-top: 100px;
            color: #e0e0e0;
            border: 1px solid #33ccff;
            border-radius: 10px;
        }

        .modal-header {
            border-bottom: 1px solid #223366;
            color: #33ccff;
        }
        .modal-header .modal-title {
            font-weight: 600;
        }

        .modal-footer {
            border-top: 1px solid #223366;
        }

        .btn-close {
            filter: invert(1) grayscale(100%) brightness(200%);
        }
        .modal-body h6 {
            color: #66ccff;
            margin-top: 1rem;
            font-weight: bold;
        }
        .modal-body ul {
            padding-left: 1.5rem;
        }
        .modal-body ul li {
            margin-bottom: 0.5rem;
        }

        /* Accordion Styling */
        .accordion-item {
            background-color: #0a0a1f;
            border: 1px solid #223366;
            margin-bottom: 0.5rem; /* Khoảng cách giữa các item */
            border-radius: 8px !important; /* Bo tròn cho accordion item */
            overflow: hidden; /* Đảm bảo bo tròn áp dụng */
        }
        .accordion-header button {
            background-color: #0f0f28;
            color: #99ccff;
            font-weight: 500;
            border-radius: 0 !important; /* Bỏ bo tròn mặc định của button */
        }
        .accordion-header button:not(.collapsed) {
            background-color: #141432;
            color: #33ccff;
            box-shadow: inset 0 -1px 0 #223366;
        }
        .accordion-header button:focus {
            box-shadow: 0 0 0 0.25rem rgba(51, 204, 255, 0.25);
        }
        .accordion-body {
            background-color: #070718;
            color: #b0b0c0;
            padding: 1.25rem;
            border-top: 1px solid #223366;
        }
        .accordion-button::after { /* Tùy chỉnh icon mũi tên */
            filter: invert(80%) sepia(100%) saturate(500%) hue-rotate(180deg) brightness(150%) contrast(100%);
        }


        /* Gallery Styling */
        .gallery-img {
            cursor: pointer;
            transition: transform 0.3s ease, opacity 0.3s ease, box-shadow 0.3s ease;
            border-radius: 8px;
            border: 2px solid transparent;
        }

        .gallery-img:hover {
            transform: scale(1.05);
            opacity: 0.85;
            box-shadow: 0 0 15px rgba(51, 204, 255, 0.5);
            border-color: #33ccff;
        }
        #modalImageDisplay {
            max-height: 80vh;
            border-radius: 8px;
        }