/* ===== БАЗОВЫЕ СТИЛИ ===== */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-size: 24px;
        }

        /* Стили для спрайт-контейнера */

        .sprite-frame {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        object-fit: contain;
        opacity: 0;
        }

        /* .frame-1 { animation-delay: 0s; }
        .frame-2 { animation-delay: 1s; }
        .frame-3 { animation-delay: 2s; }
        .frame-4 { animation-delay: 3s; }
        .frame-5 { animation-delay: 4s; }
        .frame-6 { animation-delay: 5s; } */

        @keyframes spriteCycle {
        0% { background: url(/images/1.jpg); }
        25% { background: url(/images/3.jpg); }
        50% { background: url(/images/4.jpg); }
        75% { background: url(/images/5.jpg); }
        100% { background: url(/images/1.jpg); }
        }


        body {
            font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
            line-height: 1.6;
            color: #222;
            background-color: #f9f9f9;
            padding: 20px;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            overflow: auto;
            height: 100vh;
            align-items: center;
            
        }
        
        @media (max-width: 600px) {
            * {
                font-size: 16px;
            }
         }


        .container {
            max-width: 90vw;
            margin: 0 auto;
            background: white;
            border-radius: 24px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.05);
            padding: 40px;
        }

        .page-title {
            font-size: 2rem;
            font-weight: 600;
            margin-bottom: 0.5rem;
            color: #003057;
            border-bottom: 2px solid #eaeef2;
            padding-bottom: 0.5rem;
        }

        .subtitle {
            font-size: 1.1rem;
            color: #4a5b6e;
            margin-bottom: 2rem;
        }

.site-header {
    background-color: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 100;
    border-radius: 60px 60px 0 0;
    margin-bottom: 20px;
    width: 100vw;
}

.header-container {
    max-width: 80vw;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap; 
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: #003057;
    transition: 0.3s ease;
}




/* Стили для спрайт-контейнера уже есть выше в вашем коде, они правильные */
.logo-text {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.header-nav {
    display: flex;
    gap: 30px;
    flex-wrap: wrap;
}

.nav-link {
    color: #003057;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
    border-bottom: 2px solid transparent;
    padding-bottom: 4px;
}

.nav-link:hover {
    color: #0066cc;
    border-bottom-color: #0066cc;
}

.sprite-container {
    border-radius: 20px;
    width: 120px;               /* размер под ваш логотип */
    height: 120px;
    background-size: contain;   /* чтобы картинка влезла без искажений */
    background-repeat: no-repeat;
    background-position: center;
    animation: changeBg 15s infinite ease; /* steps(1) — резкая смена */
    transition: all 0.5s ease;
    
}

.logo:hover {
     color: green;
}

@keyframes changeBg {
    0%   { background-image: url('/images/1.jpg'); }
    20%  { background-image: url('/images/3.jpg'); } /* 20% = 1/5 времени */
    40%  { background-image: url('/images/4.jpg'); }
    60%  { background-image: url('/images/5.jpg'); }
    80%  { background-image: url('/images/6.jpg'); }
    100% { background-image: url('/images/1.jpg'); } /* возврат к первому */
}

        /* ===== СТИЛИ ФУТЕРА ===== */
        .site-footer {
            background-color: white;
            box-shadow: 0 -2px 10px rgba(0,0,0,0.05);
            padding: 30px 0;
            margin-top: 20px;
            border-radius: 0 0 60px 60px;
            height: 100px;
            width: 100vw;
        }

        .footer-container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
            display: flex;
            justify-content: center;
            gap: 60px;
            flex-wrap: wrap;
        }

        .footer-item {
            display: flex;
            align-items: center;
            gap: 10px;
            color: #003057;
            font-size: 1.1rem;
        }

        .footer-item a {
            color: #003057;
            text-decoration: none;
            transition: color 0.2s;
            border-bottom: 1px dotted transparent;
        }

        .footer-item a:hover {
            color: #0066cc;
            border-bottom-color: #0066cc;
        }

        /* ===== СТИЛИ ДЛЯ ОСНОВНЫХ DETAILS (ПЕРВЫЙ УРОВЕНЬ) ===== */
        .container > details {
            border-bottom: 1px solid #eaeef2;
            padding: 16px 0;
        }
        .container > details:first-of-type {
            border-top: 1px solid #eaeef2;
        }

        .container > details > summary {
            font-weight: 600;
            font-size: 1.1rem;
            cursor: pointer;
            list-style: none;
            display: flex;
            align-items: center;
            justify-content: space-between;
            color: #003057;
            padding: 4px 0;
            transition: color 0.2s;
        }
        .container > details > summary:hover {
            color: #001b3a;
        }

        .container > details > summary::-webkit-details-marker {
            display: none;
        }
        .container > details > summary::after {
            content: '▶';
            font-size: 0.8rem;
            color: #0066cc;
            transition: transform 0.2s;
            margin-left: 8px;
        }
        .container > details[open] > summary::after {
            transform: rotate(90deg);
        }

        /* ===== СТИЛИ ДЛЯ ВЛОЖЕННЫХ DETAILS ===== */
        .details-content details {
            border: none;
            margin: 8px 0 8px 20px;
            padding: 0;
        }
        .details-content details summary {
            font-weight: 500;
            font-size: 1rem;
            cursor: pointer;
            list-style: none;
            display: flex;
            align-items: center;
            justify-content: space-between;
            color: #1e4660;
            padding: 8px 0;
            border-bottom: 1px dashed #d0dde8;
        }
        .details-content details summary::-webkit-details-marker {
            display: none;
        }
        .details-content details summary::after {
            content: '▶';
            font-size: 0.7rem;
            color: #0066cc;
            transition: transform 0.2s;
            margin-left: 8px;
        }
        .details-content details[open] > summary::after {
            transform: rotate(90deg);
        }

        .details-content details .details-content {
            padding-left: 16px;
            border-left: 2px solid #eaeef2;
            margin: 8px 0 12px 0;
        }

        /* ===== ТАБЛИЦЫ И СПИСКИ ===== */
        .simple-table {
            width: 100%;
            border-collapse: collapse;
            margin: 15px 0;
            font-size: 0.95rem;
        }
        .simple-table th {
            background-color: #f0f5fa;
            font-weight: 600;
            text-align: left;
            padding: 8px 12px;
            border: 1px solid #d0dde8;
        }
        .simple-table td {
            padding: 8px 12px;
            border: 1px solid #d0dde8;
        }

        .lesson-list {
            list-style: none;
            padding-left: 0;
        }
        .lesson-list li {
            padding: 4px 0 4px 24px;
            position: relative;
        }
        .lesson-list li::before {
            content: '•';
            color: #0066cc;
            font-weight: bold;
            position: absolute;
            left: 8px;
        }

        main {
            flex: 1;
            overflow: auto;
            width: 90vw;
        }

        /* Адаптивность */
        @media (max-width: 600px) {
           main {
               width: 90vw;
           }
            
            .header-container {
                flex-direction: column;
                gap: 15px;
            }
            .header-nav {
                gap: 20px;
            }
            .footer-container {
                flex-direction: column;
                align-items: center;
                gap: 20px;
            }
            .container {
                padding: 20px;
            }
            
            .sprite-container {
                width: 80px;
                height: 80px;
            }
        }    
           
        
        .pdf-viewer {
            width: 100%;
            height: 600px;
            border: 1px solid #d0dde8;
            border-radius: 12px;
            margin: 20px 0;
        }

        .consent-block {
            background-color: #f8fafc;
            border-radius: 12px;
            padding: 20px;
            margin: 20px 0;
            display: flex;
            align-items: center;
            gap: 15px;
            flex-wrap: wrap;
        }

        .consent-block input[type="checkbox"] {
            width: 24px;
            height: 24px;
            cursor: pointer;
        }

        .consent-block label {
            font-size: 1rem;
            color: #003057;
            cursor: pointer;
            flex: 1;
        }

        .download-btn {
            background-color: #0066cc;
            color: white;
            border: none;
            border-radius: 60px;
            padding: 12px 30px;
            font-size: 1.2rem;
            font-weight: 500;
            cursor: pointer;
            transition: background-color 0.2s;
            border: 2px solid transparent;
        }

        .download-btn:hover {
            background-color: #003057;
        }

        .download-btn:disabled {
            background-color: #cccccc;
            cursor: not-allowed;
        }

        .message {
            margin-top: 15px;
            color: #cc3300;
            font-weight: 500;
            min-height: 2rem;
        }

        /* Адаптивность */
        @media (max-width: 600px) {
            .header-container {
                flex-direction: column;
                gap: 15px;
                width: 100%;
            }
            .header-nav {
                gap: 20px;
            }
            .footer-container {
                flex-direction: column;
                align-items: center;
                gap: 20px;
                width: 100%;
            }
            .pdf-viewer {
                height: 400px;
            }
            .consent-block {
                flex-direction: column;
                align-items: flex-start;
            }
        }