html {
        font-size: 16px;
    }

    /* arrow to top */
    #backToTop {
        position: fixed;
        bottom: 20px;
        right: 20px;
        width: 50px;
        height: 50px;
        background-color: #007bff;
        color: white;
        text-align: center;
        line-height: 50px;
        font-size: 24px;
        border-radius: 50%;
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        cursor: pointer;
        display: none;
        /* Изначально скрываем */
        z-index: 1000;
    }

    #backToTop:hover {
        background-color: #0056b3;
    }

    /* Animation service-box */

    /* Initial state */
    .animate-title,
    .animate-service-box {
        opacity: 0;
        transform: translateY(100px);
        transition: opacity 1s ease-out, transform 1s ease-out;
    }

    /* Active state */
    .animate-title.observed,
    .animate-service-box.observed {
        opacity: 1;
        transform: translateY(0);
    }

    .text-link {
        color: white;
    }

    .service-box {
        transition: transform 0.3s ease, background-color 0.3s ease, color 0.3s ease;
    }

    .service-box:hover {
        transform: translateY(-10px);
        background-color: #f3f4f6;
    }

    .service-box:hover h4,
    .service-box:hover p {
        color: #6b7280;
    }

    .service-box:hover .text-link {
        color: #1d4ed8;
    }

    /* Стили для видео и текста поверх него */
    .video-container {
        position: relative;
        z-index: 0;
        display: flex;
        align-items: center;
        justify-content: center;
        height: 70vh;
        margin: 0 auto;
        overflow: hidden;
    }

    .video-overlay {
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);
        text-align: center;
        z-index: 2;
        pointer-events: none;
    }

    .video-overlay h2 {
        color: white;
        margin: 0;
        font-size: 2rem;
        text-shadow: 2px 2px 8px rgba(0, 0, 0, 0.7);
    }

    video {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        object-fit: cover;
        z-index: 1;
    }


    /* Стили для кнопки главного экрана */
    .primary-button {
        transition: transform 0.3s ease, background-color 0.3s ease, color 0.3s ease;
    }

    .primary-button:hover {
        transform: translateY(5px);
        background-color: #002766;
    }

    .logo-img {
        transition: all 0.3s ease-in-out;
    }

    .logo-img:hover {
        content: url('/images/logo-hover.svg');
    }

    .menu-toggle {
        margin-bottom: 1rem;
        width: 100%;
        display: flex;
        align-items: center;
        justify-content: space-between;
    }

    .main-screen {
        display: flex;
        justify-content: flex-end;
        align-items: center;
    }

    /* Intersection Observer Animation using CSS */
    @keyframes fadeInUp {
        0% {
            opacity: 0;
            transform: translateY(100px);
        }

        100% {
            opacity: 1;
            transform: translateY(0);
        }
    }

    .animate-title.observed,
    .animate-service-box.observed {
        animation: fadeInUp 1s forwards;
    }

    .active {
        color: #2563eb;
        /* Синий цвет */
        text-decoration: underline;
        /* Подчёркивание */
    }

    .logo {
        transition: 0.3s ease-in-out;
    }

    .logo:hover {
        content: url("/images/logo-hover.svg");
    }

    .hidden {
        display: none;
    }
    
    .error-message {
        color: red;
        font-weight: bold;
        margin-top: 10px;
    }