* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #069494 0%, #9EFCFF 100%);
    min-height: 100vh;
    padding: 40px 20px;
    color: #333;
    line-height: 1.6;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
}

.header {
    text-align: center;
    margin-bottom: 40px;
    color: white;
}

.header h1 {
    font-size: 2.8rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.header p {
    font-size: 1.2rem;
    opacity: 0.9;
    font-weight: 300;
}

/* Стили для тем */
.topics-container {
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 15px 40px rgba(0,0,0,0.15);
}

.topic {
    border-bottom: 1px solid #eee;
}

.topic:last-child {
    border-bottom: none;
}

.topic-header {
    display: flex;
    align-items: center;
    padding: 25px 30px;
    cursor: pointer;
    list-style: none;
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    transition: all 0.3s ease;
}

.topic-header:hover {
    background: linear-gradient(135deg, #e9ecef 0%, #dee2e6 100%);
}

.topic-header::-webkit-details-marker {
    display: none;
}

.topic-icon {
    font-size: 2rem;
    margin-right: 20px;
    width: 50px;
    text-align: center;
}

.topic-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #495057;
    flex: 1;
}

.topic-count {
    background: #6c757d;
    color: white;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

/* Стили для списка презентаций */
.presentations-list {
    padding: 0;
}

.presentation-link {
    display: flex;
    align-items: center;
    padding: 20px 30px;
    text-decoration: none;
    color: inherit;
    border-bottom: 1px solid #f8f9fa;
    transition: all 0.2s ease;
}

.presentation-link:hover {
    background-color: #f8f9fa;
    transform: translateX(5px);
}

.presentation-link:last-child {
    border-bottom: none;
}

.presentation-icon {
    font-size: 1.5rem;
    margin-right: 20px;
    width: 40px;
    text-align: center;
}

.presentation-info {
    flex: 1;
}

.presentation-info h3 {
    font-size: 1.2rem;
    font-weight: 600;
    color: #212529;
    margin-bottom: 5px;
}

.presentation-info p {
    color: #6c757d;
    font-size: 0.95rem;
    line-height: 1.5;
}

.presentation-arrow {
    color: #6c757d;
    font-size: 1.2rem;
    font-weight: bold;
    margin-left: 15px;
    transition: transform 0.2s ease;
}

.presentation-link:hover .presentation-arrow {
    transform: translateX(3px);
    color: #495057;
}

/* Анимации */
@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.presentation-link {
    animation: slideDown 0.3s ease forwards;
}

/* .presentation-link:nth-child(1) { animation-delay: 0.1s; }
.presentation-link:nth-child(2) { animation-delay: 0.2s; }
.presentation-link:nth-child(3) { animation-delay: 0.3s; } */

.footer {
    text-align: center;
    margin-top: 40px;
    color: white;
    opacity: 0.8;
    font-size: 0.9rem;
}

/* Адаптивность */
@media (max-width: 768px) {
    body {
        padding: 20px 15px;
    }
    
    .header h1 {
        font-size: 2.2rem;
    }
    
    .topic-header {
        padding: 20px;
    }
    
    .topic-icon {
        font-size: 1.5rem;
        margin-right: 15px;
    }
    
    .topic-header h2 {
        font-size: 1.3rem;
    }
    
    .presentation-link {
        padding: 15px 20px;
        flex-direction: column;
        align-items: flex-start;
    }
    
    .presentation-icon {
        margin-right: 0;
        margin-bottom: 10px;
    }
    
    .presentation-arrow {
        align-self: flex-end;
        margin-top: 10px;
        margin-left: 0;
    }
}